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Ingy döt Net 2023-07-01 11:58:00 -04:00
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---
category:
- Mathematics
from: http://rosettacode.org/wiki/Left_factorials

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'''Left factorials''', &nbsp; <big><big>!n</big></big>, &nbsp; may refer to either &nbsp; ''subfactorials'' &nbsp; or to &nbsp; ''factorial sums'';
<br>the same notation can be confusingly seen being used for the two different definitions.
Sometimes, &nbsp; ''subfactorials'' &nbsp; (also known as ''derangements'') &nbsp; may use any of the notations:
:::::::* &nbsp; <big><big> <b> <span style="font-family:serif">!''n''`</span> </b> </big></big>
:::::::* &nbsp; <big><big> <b> <span style="font-family:serif">!''n''</span> </b> </big></big>
:::::::* &nbsp; <big><big> <b> <span style="font-family:serif">''n''¡</span> </b> </big></big>
(It may not be visually obvious, but the last example uses an upside-down exclamation mark.)
This Rosetta Code task will be using this formula &nbsp; (''factorial sums'') &nbsp; for &nbsp; '''left factorial''':
<big><big>
::::: &nbsp; <math> !n = \sum_{k=0}^{n-1} k! </math>
</big></big>
:::: where
<big><big>
::::: &nbsp; <math>!0 = 0</math>
</big></big>
;Task
Display the left factorials for:
* &nbsp; zero through ten &nbsp; &nbsp; (inclusive)
* &nbsp; 20 &nbsp; through &nbsp; 110 &nbsp; (inclusive) &nbsp; by tens
<br>
Display the length (in decimal digits) of the left factorials for:
* &nbsp; 1,000 &nbsp; through &nbsp; 10,000 &nbsp; (inclusive), by thousands.
;Also see:
* &nbsp; The OEIS entry: [http://oeis.org/A003422 A003422 left factorials]
* &nbsp; The MathWorld entry: [http://mathworld.wolfram.com/LeftFactorial.html left factorial]
* &nbsp; The MathWorld entry: [http://mathworld.wolfram.com/FactorialSums.html factorial sums]
* &nbsp; The MathWorld entry: [http://mathworld.wolfram.com/Subfactorial.html subfactorial]
;Related task:
* &nbsp; [http://rosettacode.org/wiki/Permutations/Derangements permutations/derangements (subfactorials)]
<br><br>

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F left_fact(n)
BigInt result = 0
BigInt factorial = 1
L(i) 1 .. n
result += factorial
factorial *= i
R result
print(First 11 left factorials:)
print((0..10).map(i -> left_fact(i)))
print("\n20 through 110 (inclusive) by tens:")
L(i) (20..110).step(10)
print(left_fact(i))
print("\nDigits in 1,000 through 10,000 by thousands:")
print((1000..10000).step(1000).map(i -> String(left_fact(i)).len))

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# set the precision of LONG LONG INT - large enough for !n up to ! 10 000 #
PR precision 36000 PR
# stores left factorials in an array #
# we calculate the left factorials, storing their values in the "values" array #
# if step is <= 1, we store we store every left factorial, otherwise we store !x when x MOD step = 0 #
# note this means values[ 0 ] is always !0 #
PROC get left factorials = ( REF[]LONG LONG INT values, INT step )VOID:
BEGIN
INT store position := LWB values;
INT max values := UPB values;
LONG LONG INT result := 0;
LONG LONG INT factorial k := 1;
FOR k FROM 0
WHILE
IF IF step <= 1 THEN TRUE ELSE k MOD step = 0 FI THEN
values[ store position ] := result;
store position +:= 1
FI;
store position <= max values
DO
result +:= factorial k;
factorial k *:= ( k + 1 )
OD
END # get left factorials # ;
# returns the number of digits in n #
OP DIGITCOUNT = ( LONG LONG INT n )INT:
BEGIN
INT result := 1;
LONG LONG INT v := ABS n;
WHILE v > 100 000 000 DO
result +:= 8;
v OVERAB 100 000 000
OD;
WHILE v > 10 DO
result +:= 1;
v OVERAB 10
OD;
result
END # DIGITCOUNT # ;
BEGIN
print( ( "!n for n = 0(1)10", newline ) );
[ 0 : 10 ]LONG LONG INT v;
get left factorials( v, 1 );
FOR i FROM 0 TO UPB v DO
print( ( whole( v[ i ], 0 ), newline ) )
OD
END;
BEGIN
print( ( "!n for n = 20(10)110", newline ) );
[ 0 : 11 ]LONG LONG INT v;
get left factorials( v, 10 );
FOR i FROM 2 TO UPB v DO
print( ( whole( v[ i ], 0 ), newline ) )
OD
END;
BEGIN
print( ( "digit counts of !n for n = 1000(1000)10 000", newline ) );
[ 0 : 10 ]LONG LONG INT v;
get left factorials( v, 1 000 );
FOR i FROM 1 TO UPB v DO
print( ( whole( DIGITCOUNT v[ i ], 0 ), newline ) )
OD
END

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#!/usr/bin/gawk -Mf
function left_factorial(num) {
result=0
adder=1
if (num==0) return(0)
for (k = 1; k <=num; k++) {
result = result + adder
adder = adder * k
}
return(result)
}
BEGIN {
for (i = 0; i <= 10; i++) {
print "!" i " = " left_factorial(i)
}
for (i = 20; i<= 110; i+=10) {
print "!" i " = " left_factorial(i)
}
for (i = 1000; i<= 10000; i+=1000) {
print "!" i " has " length(left_factorial(i)) " digits"
}
}

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lfactorial: function [n][
if zero? n -> return 0
fold 0..dec n [x y] -> x + factorial y
]
print "First eleven:"
0..10 | map => lfactorial
| print
print "\n20th through 110th by tens:"
r: range.step: 10 20 110
r | map => lfactorial
| loop => print
print "\nDigits in 1,000th through 10,000th by thousands:"
r: range.step: 1000 1000 10000
r | map'x -> size ~"|lfactorial x|"
| print

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INSTALL @lib$+"BB4WMAPMLIB" : PROCMAPM_Init : MAPM_Dec%=200
Result$="0" : A$="1"
FOR I%=0 TO 10000
IF I% Result$=FNMAPM_Add(Result$,A$) : A$=FNMAPM_Multiply(A$,STR$I%)
IF I% < 111 IF I% MOD 10 = 0 OR I% < 11 PRINT "!";I% " = " FNMAPM_FormatDec(Result$,0)
IF I% > 999 IF I% MOD 1000 = 0 PRINT "!";I% " has " LENFNMAPM_FormatDec(Result$,0) " digits"
NEXT
END

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( ( leftFact
= result factorial i
. 0:?result
& 1:?factorial
& 0:?i
& whl
' ( !i+1:~>!arg:?i
& !factorial+!result:?result
& !factorial*!i:?factorial
)
& !result
)
& ( iterate
= from to step c fun
. !arg:(?from.?to.?step.?fun)
& !from+-1*!step:?from
& !step:?c
& whl
' ( !step+!from:~>!to:?from
& !fun$(leftFact$!from)
)
&
)
& out$"First 11 left factorials:"
& iterate$(0.10.1.out)
& out$"
20 through 110 (inclusive) by tens:"
& iterate$(20.110.10.out)
& out$"
Digits in 1,000 through 10,000 by thousands:"
& iterate
$ ( 1000
. 10000
. 1000
. (=L.@(!arg:? [?L)&out$!L)
)
)

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#include <vector>
#include <string>
#include <algorithm>
#include <iostream>
#include <sstream>
using namespace std;
#if 1 // optimized for 64-bit architecture
typedef unsigned long usingle;
typedef unsigned long long udouble;
const int word_len = 32;
#else // optimized for 32-bit architecture
typedef unsigned short usingle;
typedef unsigned long udouble;
const int word_len = 16;
#endif
class bignum {
private:
// rep_.size() == 0 if and only if the value is zero.
// Otherwise, the word rep_[0] keeps the least significant bits.
vector<usingle> rep_;
public:
explicit bignum(usingle n = 0) { if (n > 0) rep_.push_back(n); }
bool equals(usingle n) const {
if (n == 0) return rep_.empty();
if (rep_.size() > 1) return false;
return rep_[0] == n;
}
bignum add(usingle addend) const {
bignum result(0);
udouble sum = addend;
for (size_t i = 0; i < rep_.size(); ++i) {
sum += rep_[i];
result.rep_.push_back(sum & (((udouble)1 << word_len) - 1));
sum >>= word_len;
}
if (sum > 0) result.rep_.push_back((usingle)sum);
return result;
}
bignum add(const bignum& addend) const {
bignum result(0);
udouble sum = 0;
size_t sz1 = rep_.size();
size_t sz2 = addend.rep_.size();
for (size_t i = 0; i < max(sz1, sz2); ++i) {
if (i < sz1) sum += rep_[i];
if (i < sz2) sum += addend.rep_[i];
result.rep_.push_back(sum & (((udouble)1 << word_len) - 1));
sum >>= word_len;
}
if (sum > 0) result.rep_.push_back((usingle)sum);
return result;
}
bignum multiply(usingle factor) const {
bignum result(0);
udouble product = 0;
for (size_t i = 0; i < rep_.size(); ++i) {
product += (udouble)rep_[i] * factor;
result.rep_.push_back(product & (((udouble)1 << word_len) - 1));
product >>= word_len;
}
if (product > 0)
result.rep_.push_back((usingle)product);
return result;
}
void divide(usingle divisor, bignum& quotient, usingle& remainder) const {
quotient.rep_.resize(0);
udouble dividend = 0;
remainder = 0;
for (size_t i = rep_.size(); i > 0; --i) {
dividend = ((udouble)remainder << word_len) + rep_[i - 1];
usingle quo = (usingle)(dividend / divisor);
remainder = (usingle)(dividend % divisor);
if (quo > 0 || i < rep_.size())
quotient.rep_.push_back(quo);
}
reverse(quotient.rep_.begin(), quotient.rep_.end());
}
};
ostream& operator<<(ostream& os, const bignum& x);
ostream& operator<<(ostream& os, const bignum& x) {
string rep;
bignum dividend = x;
bignum quotient;
usingle remainder;
while (true) {
dividend.divide(10, quotient, remainder);
rep += (char)('0' + remainder);
if (quotient.equals(0)) break;
dividend = quotient;
}
reverse(rep.begin(), rep.end());
os << rep;
return os;
}
bignum lfact(usingle n);
bignum lfact(usingle n) {
bignum result(0);
bignum f(1);
for (usingle k = 1; k <= n; ++k) {
result = result.add(f);
f = f.multiply(k);
}
return result;
}
int main() {
for (usingle i = 0; i <= 10; ++i) {
cout << "!" << i << " = " << lfact(i) << endl;
}
for (usingle i = 20; i <= 110; i += 10) {
cout << "!" << i << " = " << lfact(i) << endl;
}
for (usingle i = 1000; i <= 10000; i += 1000) {
stringstream ss;
ss << lfact(i);
cout << "!" << i << " has " << ss.str().size()
<< " digits." << endl;
}
}

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#include <iostream>
#include <gmpxx.h>
template <typename integer>
class left_factorial_generator {
public:
integer next() {
integer result = next_;
next_ += factorial_;
factorial_ *= n_++;
return result;
}
private:
unsigned int n_ = 1;
integer factorial_ = 1;
integer next_ = 0;
};
int main() {
left_factorial_generator<mpz_class> lf;
int i = 0;
std::cout << "Left factorials 0 through 10:\n";
for (; i <= 10; ++i)
std::cout << "!" << i << " = " << lf.next() << '\n';
std::cout << "Left factorials 20 through 110, by tens:\n";
for (; i <= 110; ++i) {
auto n = lf.next();
if (i % 10 == 0)
std::cout << "!" << i << " = " << n << '\n';
}
std::cout << "Lengths of left factorials 1000 through 10000, by thousands:\n";
for (; i <= 10000; ++i) {
auto n = lf.next();
if (i % 1000 == 0)
std::cout << "length of !" << i << " = " << n.get_str().size() << '\n';
}
return 0;
}

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using System;
using System.Numerics;
namespace LeftFactorial
{
class Program
{
static void Main(string[] args)
{
for (int i = 0; i <= 10; i++)
{
Console.WriteLine(string.Format("!{0} = {1}", i, LeftFactorial(i)));
}
for (int j = 20; j <= 110; j += 10)
{
Console.WriteLine(string.Format("!{0} = {1}", j, LeftFactorial(j)));
}
for (int k = 1000; k <= 10000; k += 1000)
{
Console.WriteLine(string.Format("!{0} has {1} digits", k, LeftFactorial(k).ToString().Length));
}
Console.ReadKey();
}
private static BigInteger Factorial(int number)
{
BigInteger accumulator = 1;
for (int factor = 1; factor <= number; factor++)
{
accumulator *= factor;
}
return accumulator;
}
private static BigInteger LeftFactorial(int n)
{
BigInteger result = 0;
for (int i = 0; i < n; i++)
{
result += Factorial(i);
}
return result;
}
}
}

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using System;
using System.Numerics;
namespace LeftFactorial
{
class Program
{
static void Main(string[] args)
{
for (int i = 0; i <= 10; i++)
{
Console.WriteLine(string.Format("!{0} : {1}", i, LeftFactorial(i)));
}
for (int j = 20; j <= 110; j += 10)
{
Console.WriteLine(string.Format("!{0} : {1}", j, LeftFactorial(j)));
}
for (int k = 1000; k <= 10000; k += 1000)
{
Console.WriteLine(string.Format("!{0} : has {1} digits", k, LeftFactorial(k).ToString().Length));
}
Console.ReadKey();
}
private static BigInteger LeftFactorial(int n)
{
BigInteger result = 0;
BigInteger subResult = 1;
for (int i = 0; i < n; i++)
{
if (i == 0)
{
subResult = 1;
}
else
{
subResult *= i;
}
result += subResult;
}
return result;
}
}
}

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <gmp.h>
void mpz_left_fac_ui(mpz_t rop, unsigned long op)
{
mpz_t t1;
mpz_init_set_ui(t1, 1);
mpz_set_ui(rop, 0);
size_t i;
for (i = 1; i <= op; ++i) {
mpz_add(rop, rop, t1);
mpz_mul_ui(t1, t1, i);
}
mpz_clear(t1);
}
size_t mpz_digitcount(mpz_t op)
{
/* mpz_sizeinbase can not be trusted to give accurate base 10 length */
char *t = mpz_get_str(NULL, 10, op);
size_t ret = strlen(t);
free(t);
return ret;
}
int main(void)
{
mpz_t t;
mpz_init(t);
size_t i;
for (i = 0; i <= 110; ++i) {
if (i <= 10 || i % 10 == 0) {
mpz_left_fac_ui(t, i);
gmp_printf("!%u = %Zd\n", i, t);
}
}
for (i = 1000; i <= 10000; i += 1000) {
mpz_left_fac_ui(t, i);
printf("!%u has %u digits\n", i, mpz_digitcount(t));
}
mpz_clear(t);
return 0;
}

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(ns left-factorial
(:gen-class))
(defn left-factorial [n]
" Compute by updating the state [fact summ] for each k, where k equals 1 to n
Update is next state is [k*fact (summ+k)"
(second
(reduce (fn [[fact summ] k]
[(*' fact k) (+ summ fact)])
[1 0] (range 1 (inc n)))))
(doseq [n (range 11)]
(println (format "!%-3d = %5d" n (left-factorial n))))
(doseq [n (range 20 111 10)]
(println (format "!%-3d = %5d" n (biginteger (left-factorial n)))))
(doseq [n (range 1000 10001 1000)]
(println (format "!%-5d has %5d digits" n (count (str (biginteger (left-factorial n)))))))

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(defun fact (n)
(reduce #'* (loop for i from 1 to n collect i)))
(defun left-fac (n)
(reduce #'+ (loop for i below n collect (fact i))))
(format t "0 -> 10~&")
(format t "~a~&" (loop for i upto 10 collect (left-fac i)))
(format t "20 -> 110 by 10~&")
(format t "~{~a~&~}" (loop for i from 20 upto 110 by 10 collect (left-fac i)))
(format t "1000 -> 10000 by 1000~&")
(format t "~{~a digits~&~}" (loop for i from 1000 upto 10000 by 1000 collect (length (format nil "~a" (left-fac i)))))

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import std.stdio, std.bigint, std.range, std.algorithm, std.conv;
BigInt leftFact(in uint n) pure nothrow /*@safe*/ {
BigInt result = 0, factorial = 1;
foreach (immutable i; 1 .. n + 1) {
result += factorial;
factorial *= i;
}
return result;
}
void main() {
writeln("First 11 left factorials:\n", 11.iota.map!leftFact);
writefln("\n20 through 110 (inclusive) by tens:\n%(%s\n%)",
iota(20, 111, 10).map!leftFact);
writefln("\nDigits in 1,000 through 10,000 by thousands:\n%s",
iota(1_000, 10_001, 1_000).map!(i => i.leftFact.text.length));
}

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(lib 'bigint)
(define (!n n)
(if (zero? n) 0
(+ (!n (1- n)) (factorial (1- n)))))
(remember '!n)

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(for ((n 11)) (printf "!n(%d) = %d" n (!n n)))
(for ((n (in-range 20 120 10))) (printf "!n(%d) = %d" n (!n n)))
!n(0) = 0
!n(1) = 1
!n(2) = 2
!n(3) = 4
!n(4) = 10
!n(5) = 34
!n(6) = 154
!n(7) = 874
!n(8) = 5914
!n(9) = 46234
!n(10) = 409114
!n(20) = 128425485935180314
!n(30) = 9157958657951075573395300940314
!n(40) = 20935051082417771847631371547939998232420940314
!n(50) = 620960027832821612639424806694551108812720525606160920420940314
!n(60) = 141074930726669571000530822087000522211656242116439949000980378746128920420940314
!n(70) = 173639511802987526699717162409282876065556519849603157850853034644815111221599509216528920420940314
!n(80) = 906089587987695346534516804650290637694024830011956365184327674619752094289696314882008531991840922336528920420940314
!n(90) = 16695570072624210767034167688394623360733515163575864136345910335924039962404869510225723072235842668787507993136908442336528920420940314
!n(100) = 942786239765826579160595268206839381354754349601050974345395410407078230249590414458830117442618180732911203520208889371641659121356556442336528920420940314
!n(110) = 145722981061585297004706728001906071948635199234860720988658042536179281328615541936083296163475394237524337422204397431927131629058103519228197429698252556442336528920420940314
; Compute !n : 5 seconds
(for ((n (in-range 1000 10001 500))) (!n n) (writeln n))
; Display results : 12 seconds
(for ((n (in-range 1000 10001 1000))) (printf "Digits of !n(%d) = %d" n (number-length (!n n))))
Digits of !n(1000) = 2565
Digits of !n(2000) = 5733
Digits of !n(3000) = 9128
Digits of !n(4000) = 12670
Digits of !n(5000) = 16322
Digits of !n(6000) = 20062
Digits of !n(7000) = 23875
Digits of !n(8000) = 27749
Digits of !n(9000) = 31678
Digits of !n(10000) = 35656

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defmodule LeftFactorial do
def calc(0), do: 0
def calc(n) do
{result, _factorial} = Enum.reduce(1..n, {0, 1}, fn i,{res, fact} ->
{res + fact, fact * i}
end)
result
end
end
Enum.each(0..10, fn i ->
IO.puts "!#{i} = #{LeftFactorial.calc(i)}"
end)
Enum.each(Enum.take_every(20..110, 10), fn i ->
IO.puts "!#{i} = #{LeftFactorial.calc(i)}"
end)
Enum.each(Enum.take_every(1000..10000, 1000), fn i ->
digits = LeftFactorial.calc(i) |> to_char_list |> length
IO.puts "!#{i} has #{digits} digits"
end)

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// Generate Sequence of Left Factorials: Nigel Galloway, March 5th., 2019.
let LF=Seq.unfold(fun (Σ,n,g)->Some(Σ,(Σ+n,n*g,g+1I))) (0I,1I,1I)

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LF |> Seq.take 11|>Seq.iter(printfn "%A")

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LF |> Seq.skip 20 |> Seq.take 91 |> Seq.iteri(fun n g->if n%10=0 then printfn "%A" g)

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LF |> Seq.skip 1000 |> Seq.take 9001 |> Seq.iteri(fun n g->if n%1000=0 then printfn "%d" (string g).Length)

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USING: formatting fry io kernel math math.factorials
math.functions math.parser math.ranges sequences ;
IN: rosetta-code.left-factorials
: left-factorial ( n -- m ) <iota> [ n! ] map-sum ;
: print-left-factorials ( seq quot -- )
'[
dup left-factorial @
[ number>string "!" prepend ] dip
"%6s %-6d\n" printf
] each nl ; inline
: digit-count ( n -- count ) log10 >integer 1 + ;
: part1 ( -- ) 11 <iota> [ ] print-left-factorials ;
: part2 ( -- ) 20 110 10 <range> [ ] print-left-factorials ;
: part3 ( -- )
"Number of digits for" print
1,000 10,000 1,000 <range>
[ digit-count ] print-left-factorials ;
: main ( -- ) part1 part2 part3 ;
MAIN: main

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36000 CONSTANT #DIGITS \ Enough for !10000
CREATE S #DIGITS ALLOT S #DIGITS ERASE VARIABLE S#
CREATE F #DIGITS ALLOT F #DIGITS ERASE VARIABLE F#
1 F C! 1 F# ! \ F = 1 = 0!
\ "Bignums": represented by two cells on the stack:
\ 1) An address pointing to the least-significant unit
\ 2) An integer size representing the number of character-size units
: mod/ /mod swap ;
: B+ ( addr u addr' u' -- u'') \ Add the second "bignum" into the first
over + >R -rot over + >R ( addr' addr R:end' R:end)
swap >R 0 over R> ( addr 0 addr addr' R:end' R:end)
\ 0: Assume second has equal or more digits, as in our problem
BEGIN over R@ < WHILE \ 1: add all digits from S
dup >R C@ swap dup >R C@ ( addr c a a' R:end' R:end R:addr'* R:addr*)
+ + 10 mod/ R@ C! R> 1+ R> 1+
REPEAT R> drop ( addr c addr* addr'* R:end')
BEGIN dup R@ < WHILE \ 2: add any remaining digits from F
dup >R C@ swap >R ( addr c a' R:end' R:addr'* R:addr*)
+ 10 mod/ R@ C! R> 1+ R> 1+
REPEAT R> drop drop ( addr c addr*)
BEGIN over WHILE \ 3: add any carry digits
>R 10 mod/ ( addr m d R:addr*) R@ C! R> 1+
REPEAT rot - nip ; \ calculate travel distance, discard 0 carry
: B* ( addr u u' -- u'') \ Multiply "bignum" inplace by U'
0 2swap over >R dup >R bounds ( u' 0 addr+u addr R:addr R:u)
DO ( u' c) over I C@ * + 10 mod/ I C! LOOP
nip R> BEGIN ( c u) over WHILE \ insert carry, may have multiple digits
>R 10 mod/ R@ swap R> R@ + ( m u d addr+u R:addr) C! 1+
REPEAT nip R> ( u'' addr) drop ;
: .B ( addr u) over + BEGIN 1- \ print bignum
dup C@ [char] 0 + EMIT over over >=
UNTIL drop drop ;
: .!n 0 <# #s [char] ! hold #> 6 over - spaces type space ;
: REPORT ( n)
dup 10 <= over dup 20 111 within swap 10 mod 0= and or
IF .!n [char] = emit space S S# @ .B cr
ELSE dup 1000 mod 0=
IF .!n ." has " S# @ . ." digits" cr
ELSE drop THEN
THEN ;
: GO 0 REPORT
1 BEGIN dup 10000 <=
WHILE
S S# @ F F# @ B+ S# !
dup REPORT
dup F F# @ rot B* F# !
1+ REPEAT drop ;

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@ -0,0 +1,38 @@
MODULE LAIROTCAF !Calculates "left factorials".
CONTAINS !The usual suspects.
INTEGER*8 FUNCTION FACT(N) !Factorial, the ordinary.
INTEGER N !The number won't ever get far.
INTEGER I !The stepper.
FACT = 1 !Here we go.
DO I = 2,N !Does nothing for N < 2.
FACT = FACT*I !Perhaps this overflows.
IF (FACT.LE.0) STOP "Factorial: Overflow!" !Two's complement arithmetic.
END DO !No longer any IF OVERFLOW tests.
END FUNCTION FACT !Simple enough.
INTEGER*8 FUNCTION LFACT(N) !Left factorial.
INTEGER N !This number won't get far either.
INTEGER K !A stepper.
LFACT = 0 !Here we go.
DO K = 0,N - 1 !Apply the definition.
LFACT = LFACT + FACT(K) !Perhaps this overflows.
IF (LFACT.LE.0) STOP "Lfact: Overflow!" !Unreliable test.
END DO !On to the next step in the summation.
END FUNCTION LFACT !No attempts at saving effort.
END MODULE LAIROTCAF !Just the minimum.
PROGRAM POKE
USE LAIROTCAF
INTEGER I
WRITE (6,*) "Left factorials, from 0 to 10..."
DO I = 0,10
WRITE (6,1) I,LFACT(I)
1 FORMAT ("!",I0,T6,I0)
END DO
WRITE (6,*) "Left factorials, from 20 to 110 by tens..."
DO I = 20,110,10
WRITE (6,1) I,LFACT(I)
END DO
END

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@ -0,0 +1,67 @@
Calculates "left factorials", in sequence, and shows some.
INTEGER ENUFF,BASE !Some parameters.
PARAMETER (BASE = 10, ENUFF = 40000) !This should do.
INTEGER LF,F(ENUFF),LS,S(ENUFF) !Big numbers in digits F(1:LF), S(1:LS)
INTEGER N !A stepper.
INTEGER L !Locates digits.
INTEGER C !A carry for arithmetic.
INTEGER MSG !I/O unit number.
MSG = 6 !Standard output.
LF = 1; F(1) = 1 !Set F = 1 = 0!
LS = 1; S(1) = 0 !Set S = 0 = !0
WRITE (MSG,1) 0,0 !Pre-emptive first result.
1 FORMAT ("!",I0,T6,666I1) !This will do for reasonable sizes.
10 DO N = 1,10000 !Step away.
Commence the addition of F to S.
20 C = 0 !Clear the carry.
DO L = 1,MIN(LF,LS) !First, both S and F have low-order digits.
C = S(L) + F(L) + C !So, a three-part addition.
S(L) = MOD(C,BASE) !Place the digit.
C = C/BASE !Carry to the next digit up.
END DO !Ends with L and C important.
Careful. L fingers the next digit up, and C is to carry in to that digit.
IF (LF.GT.LS) THEN !Has F more digits than S?
DO L = L,LF !Yes. Continue adding, with leading zero digits from S.
C = F(L) + C !Thus.
LS = LS + 1 !Another digit for S.
S(LS) = MOD(C,BASE) !Place.
C = C/BASE !Carry to the next digit up.
END DO !Continue to the end of F.
END IF !Either way, F has been added in.
Continue carrying, with C for digit L.
DO WHILE(C .GT. 0) !Extend the carry into S.
IF (L.LE.LS) THEN !If F had fewer digits than S,
C = C + S(L) !S digits await.
ELSE !Otherwise,
LS = LS + 1 !Extend S.
END IF !C is ready.
S(L) = MOD(C,BASE) !Place it.
C = C/BASE !The carry for the next digit up.
L = L + 1 !Locate it.
END DO !Perhaps a multi-digit carry.
Contemplate what to do with the current S.
IF (N.LE.10) THEN !First selection: !N for 0 to 10.
WRITE (MSG,1) N,S(LS:1:-1) !Show the value. Digits from the high-order end down.
ELSE IF (20.LE.N .AND. N.LE.110) THEN !Second selection: for 20 to 110,
IF (MOD(N,10).EQ.0) WRITE (MSG,1) N,S(LS:1:-1) !Show only every tenth.
ELSE !Third selection
IF (MOD(N,1000).EQ.0) WRITE (MSG,21) N,LS !Show only the number of digits.
21 FORMAT ("!",I0," has ",I0," digits.") !Which is why BASE is only 10.
END IF !So much for the selection of output.
Calculate the next factorial, ready for the next one up.
C = 0 !Start a multiply.
DO L = 1,LF !Step up the digits to produce N! in F.
C = F(L)*N + C !A digit.
F(L) = MOD(C,BASE) !Place.
C = C/BASE !Extract the carry.
END DO !On to the next digit.
DO WHILE(C .GT. 0) !While any carry remains,
LF = LF + 1 !Add another digit to F.
IF (LF.GT.ENUFF) STOP "F overflow!" !Perhaps not.
F(LF) = MOD(C,BASE) !The digit.
C = C/BASE !Carry to the next digit up.
END DO !If there is one, as when N > BASE.
END DO !On to the next result.
END !Ends with a new factorial that won't be used.

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@ -0,0 +1,43 @@
' FB 1.05.0 Win64
#include "gmp.bi"
Sub leftFactorial(rop As __mpz_struct, op As ULong)
Dim As __mpz_struct t1
mpz_init_set_ui(@t1, 1)
mpz_set_ui(@rop, 0)
For i As ULong = 1 To op
mpz_add(@rop, @rop, @t1)
mpz_mul_ui(@t1, @t1, i)
Next
mpz_clear(@t1)
End Sub
Function digitCount(op As __mpz_struct) As ULong
Dim As ZString Ptr t = mpz_get_str(0, 10, @op)
Dim As ULong ret = Len(*t)
Deallocate(t)
Return ret
End Function
Dim As __mpz_struct t
mpz_init(@t)
For i As ULong = 0 To 110
If i <= 10 OrElse i Mod 10 = 0 Then
leftFactorial(t, i)
gmp_printf(!"!%u = %Zd\n", i, @t)
End If
Next
Print
For i As ULong = 1000 To 10000 Step 1000
leftFactorial(t, i)
Print "!"; Str(i); " has "; digitCount(t); " digits"
Next
mpz_clear(@t)
Print
Print "Press any key to quit"
Sleep

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@ -0,0 +1,20 @@
leftFactorial[n] :=
{
sum = 0
for k = 0 to n-1
sum = sum + k!
return sum
}
println["Zero through ten"]
for n = 0 to 10
println["$n\t" + leftFactorial[n]]
println["\n20 through 110"]
for n = 20 to 110 step 10
println["$n\t" + leftFactorial[n]]
println["\nlength of 1000 through 10000"]
for n = 1000 to 10000 step 1000
println["$n has " + length[toString[leftFactorial[n]]] + " digits"]

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@ -0,0 +1,45 @@
package main
import (
"fmt"
"math/big"
)
func main() {
fmt.Print("!0 through !10: 0")
one := big.NewInt(1)
n := big.NewInt(1)
f := big.NewInt(1)
l := big.NewInt(1)
next := func() { f.Mul(f, n); l.Add(l, f); n.Add(n, one) }
for ; ; next() {
fmt.Print(" ", l)
if n.Int64() == 10 {
break
}
}
fmt.Println()
for {
for i := 0; i < 10; i++ {
next()
}
fmt.Printf("!%d: %d\n", n, l)
if n.Int64() == 110 {
break
}
}
fmt.Println("Lengths of !1000 through !10000 by thousands:")
for i := 110; i < 1000; i++ {
next()
}
for {
fmt.Print(" ", len(l.String()))
if n.Int64() == 10000 {
break
}
for i := 0; i < 1000; i++ {
next()
}
}
fmt.Println()
}

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@ -0,0 +1,20 @@
leftFact :: [Integer]
leftFact = scanl (+) 0 fact
fact :: [Integer]
fact = scanl (*) 1 [1 ..]
main :: IO ()
main =
mapM_
putStrLn
[ "0 ~ 10:"
, show $ (leftFact !!) <$> [0 .. 10]
, ""
, "20 ~ 110 by tens:"
, unlines $ show . (leftFact !!) <$> [20,30 .. 110]
, ""
, "length of 1,000 ~ 10,000 by thousands:"
, show $ length . show . (leftFact !!) <$> [1000,2000 .. 10000]
, ""
]

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@ -0,0 +1,16 @@
procedure main()
every writes(lfact(0 | !10)," ")
write()
write()
every write(lfact(20 to 110 by 10))
write()
every writes(*lfact(1000 to 10000 by 1000)," ")
write()
end
procedure lfact(n)
r := 0
f := 1
every (i := !n, r +:= .f, f *:= .i)
return r
end

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@ -0,0 +1 @@
leftFact=: +/@:!@i."0

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@ -0,0 +1,34 @@
(,. leftFact) i.11
0 0
1 1
2 2
3 4
4 10
5 34
6 154
7 874
8 5914
9 46234
10 409114
(,. leftFact) 10*2+i.10x
20 128425485935180314
30 9157958657951075573395300940314
40 20935051082417771847631371547939998232420940314
50 620960027832821612639424806694551108812720525606160920420940314
60 141074930726669571000530822087000522211656242116439949000980378746128920420940314
70 173639511802987526699717162409282876065556519849603157850853034644815111221599509216528920420940314
80 906089587987695346534516804650290637694024830011956365184327674619752094289696314882008531991840922336528920420940314
90 16695570072624210767034167688394623360733515163575864136345910335924039962404869510225723072235842668787507993136908442336528920420940314
100 942786239765826579160595268206839381354754349601050974345395410407078230249590414458830117442618180732911203520208889371641659121356556442336528920420940314
110 145722981061585297004706728001906071948635199234860720988658042536179281328615541936083296163475394237524337422204397431927131629058103519228197429698252556442336528920420940314
(,. #@":@leftFact) 1000*1+i.10x
1000 2565
2000 5733
3000 9128
4000 12670
5000 16322
6000 20062
7000 23875
8000 27749
9000 31678
10000 35656

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@ -0,0 +1,33 @@
import java.math.BigInteger;
public class LeftFac{
public static BigInteger factorial(BigInteger n){
BigInteger ans = BigInteger.ONE;
for(BigInteger x = BigInteger.ONE; x.compareTo(n) <= 0; x = x.add(BigInteger.ONE)){
ans = ans.multiply(x);
}
return ans;
}
public static BigInteger leftFact(BigInteger n){
BigInteger ans = BigInteger.ZERO;
for(BigInteger k = BigInteger.ZERO; k.compareTo(n.subtract(BigInteger.ONE)) <= 0; k = k.add(BigInteger.ONE)){
ans = ans.add(factorial(k));
}
return ans;
}
public static void main(String[] args){
for(int i = 0; i <= 10; i++){
System.out.println("!" + i + " = " + leftFact(BigInteger.valueOf(i)));
}
for(int i = 20; i <= 110; i += 10){
System.out.println("!" + i + " = " + leftFact(BigInteger.valueOf(i)));
}
for(int i = 1000; i <= 10000; i += 1000){
System.out.println("!" + i + " has " + leftFact(BigInteger.valueOf(i)).toString().length() + " digits");
}
}
}

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@ -0,0 +1,5 @@
def left_factorial:
reduce range(1; .+1) as $i
# state: [i!, !i]
([1,0]; .[1] += .[0] | .[0] *= $i)
| .[1];

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@ -0,0 +1,21 @@
import "BigInt" as BigInt;
# integer input
def long_left_factorial:
reduce range(1; .+1) as $i
# state: [i!, !i]
( ["1", "0"];
.[1] = BigInt::long_add(.[0]; .[1])
| .[0] = BigInt::long_multiply(.[0]; $i | tostring) )
| .[1];
# input and gap should be integers
def long_left_factorial_lengths(gap):
reduce range(1; .+1) as $i
# state: [i!, !i, gap]
(["1", "0", []];
.[1] = BigInt::long_add(.[0]; .[1])
| .[0] = BigInt::long_multiply(.[0]; $i|tostring)
| (.[1] | tostring | length) as $lf
| if $i % gap == 0 then .[2] += [[$i, $lf]] else . end)
| .[2];

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@ -0,0 +1,3 @@
((range(0;11), (range(2; 12) * 10)) | "\(.): \(long_left_factorial)"),
(10000 | long_left_factorial_lengths(1000) | .[] | "\(.[0]): length is \(.[1])")

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@ -0,0 +1,32 @@
$ jq -r -n -L . -f Long_left_factorial.jq
0: 0
1: 1
2: 2
3: 4
4: 10
5: 34
6: 154
7: 874
8: 5914
9: 46234
10: 409114
20: 128425485935180314
30: 9157958657951075573395300940314
40: 20935051082417771847631371547939998232420940314
50: 620960027832821612639424806694551108812720525606160920420940314
60: 141074930726669571000530822087000522211656242116439949000980378746128920420940314
70: 173639511802987526699717162409282876065556519849603157850853034644815111221599509216528920420940314
80: 906089587987695346534516804650290637694024830011956365184327674619752094289696314882008531991840922336528920420940314
90: 16695570072624210767034167688394623360733515163575864136345910335924039962404869510225723072235842668787507993136908442336528920420940314
100: 942786239765826579160595268206839381354754349601050974345395410407078230249590414458830117442618180732911203520208889371641659121356556442336528920420940314
110: 145722981061585297004706728001906071948635199234860720988658042536179281328615541936083296163475394237524337422204397431927131629058103519228197429698252556442336528920420940314
1000: length is 2565
2000: length is 5733
3000: length is 9128
4000: length is 12670
5000: length is 16322
6000: length is 20062
7000: length is 23875
8000: length is 27749
9000: length is 31678
10000: length is 35656

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@ -0,0 +1,4 @@
leftfactorial(n::Integer) = n ≤ 0 ? zero(n) : sum(factorial, 0:n-1)
@show leftfactorial.(0:10)
@show ndigits.(leftfactorial.(big.(1000:1000:10_000)))

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@ -0,0 +1,23 @@
// version 1.0.6
import java.math.BigInteger
fun leftFactorial(n: Int): BigInteger {
if (n == 0) return BigInteger.ZERO
var fact = BigInteger.ONE
var sum = fact
for (i in 1 until n) {
fact *= BigInteger.valueOf(i.toLong())
sum += fact
}
return sum
}
fun main(args: Array<String>) {
for (i in 0..110)
if (i <= 10 || (i % 10) == 0)
println("!${i.toString().padEnd(3)} = ${leftFactorial(i)}")
println("\nLength of the following left factorials:")
for (i in 1000..10000 step 1000)
println("!${i.toString().padEnd(5)} has ${leftFactorial(i).toString().length} digits")
}

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@ -0,0 +1,79 @@
'''1) defining !n'''
{def !n // the main function's name
{def !n.mem {A.new 0 1 2}} // initializing a global array
// memorizing the computed values of !n
{def !n.set // computing and storing the values
{lambda {:n}
{A.set! :n // assign at n
{long_mult :n {A.get {- :n 1} {!n.mem}} } // product of n and computed value at n-1
{!n.mem}}}} // in the global array
{def !n.get // getting a value
{lambda {:n}
{A.get :n {if {W.equal? {A.get :n {!n.mem}} undefined} // if it doesn't exist
then {!n.set :n} // then compute it
else {!n.mem}}}}} // else get it from the global array
{lambda {:n} // the main function's body
{if {< :n 2} // if n=0 and n=1
then :n // then return 0 or 1
else {S.reduce long_add // apply add_long to
1 {S.map !n.get {S.serie 1 {- :n 1}}}}}}} // the sequence of computed values
'''2) the task'''
A) computing !n from 2 to 10 takes about 4ms
{S.map {lambda {:n} {br}!n(:n) = {!n :n}}
{S.serie 0 10}}
->
!n(0) = 0
!n(1) = 1
!n(2) = 2
!n(3) = 4
!n(4) = 10
!n(5) = 34
!n(6) = 154
!n(7) = 874
!n(8) = 5914
!n(9) = 46234
!n(10) = 409114
B) computing !n from 20 to 110 with step 10 takes about 25ms
{S.map {lambda {:n} {br}!n(:n) = {!n :n}}
{S.serie 20 110 10}}
->
!n(20) = 128425485935180314
!n(30) = 9157958657951075573395300940314
!n(40) = 20935051082417771847631371547939998232420940314
!n(50) = 620960027832821612639424806694551108812720525606160920420940314
!n(60) = 141074930726669571000530822087000522211656242116439949000980378746128920420940314
!n(70) = 173639511802987526699717162409282876065556519849603157850853034644815111221599509216528920420940314
!n(80) = 906089587987695346534516804650290637694024830011956365184327674619752094289696314882008531991840922336528920420940314
!n(90) = 16695570072624210767034167688394623360733515163575864136345910335924039962404869510225723072235842668787507993136908442336528920420940314
!n(100) = 942786239765826579160595268206839381354754349601050974345395410407078230249590414458830117442618180732911203520208889371641659121356556442336528920420940314
!n(110) = 145722981061585297004706728001906071948635199234860720988658042536179281328615541936083296163475394237524337422204397431927131629058103519228197429698252556442336528920420940314
C) computing !n from 1000 to 1000 with step 1000 takes about 87 seconds
1) compute n! from 1 to 10000 and store in MEM // about 86 seconds
{def foo {!n 10000}} -> foo
2) take 10 values from MEM // about 1ms
{S.map {lambda {:n}
{br}Digits of !n(:n) = {W.length {A.get {- :n 1} {MEM}}}}
{S.serie 1000 10000 1000}}
->
Digits of !n(1000) = 2565
Digits of !n(2000) = 5733
Digits of !n(3000) = 9128
Digits of !n(4000) = 12670
Digits of !n(5000) = 16322
Digits of !n(6000) = 20062
Digits of !n(7000) = 23875
Digits of !n(8000) = 27749
Digits of !n(9000) = 31678
Digits of !n(10000) = 35656

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@ -0,0 +1,28 @@
-- Lua bindings for GNU bc
require("bc")
-- Return table of factorials from 0 to n
function facsUpTo (n)
local f, fList = bc.number(1), {}
fList[0] = 1
for i = 1, n do
f = bc.mul(f, i)
fList[i] = f
end
return fList
end
-- Return left factorial of n
function leftFac (n)
local sum = bc.number(0)
for k = 0, n - 1 do sum = bc.add(sum, facList[k]) end
return bc.tostring(sum)
end
-- Main procedure
facList = facsUpTo(10000)
for i = 0, 10 do print("!" .. i .. " = " .. leftFac(i)) end
for i = 20, 110, 10 do print("!" .. i .. " = " .. leftFac(i)) end
for i = 1000, 10000, 1000 do
print("!" .. i .. " contains " .. #leftFac(i) .. " digits")
end

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@ -0,0 +1,4 @@
left_factorial := n -> add(k!, k = 1 .. n - 1);
seq(left_factorial(i), i = 1 .. 10);
seq(left_factorial(i), i = 20 .. 110, 10);
seq(length(left_factorial(i)), i = 1000 .. 10000, 1000);

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@ -0,0 +1,7 @@
left[n_] := left[n] = Sum[k!, {k, 0, n - 1}]
Print["left factorials 0 through 10:"]
Print[left /@ Range[0, 10] // TableForm]
Print["left factorials 20 through 110, by tens:"]
Print[left /@ Range[20, 110, 10] // TableForm]
Print["Digits in left factorials 1,000 through 10,000, by thousands:"]
Print[Length[IntegerDigits[left[#]]] & /@ Range[1000, 10000, 1000] // TableForm]

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@ -0,0 +1,26 @@
import iterutils, bigints
proc lfact: iterator: BigInt =
result = iterator: BigInt =
yield 0.initBigInt
var
fact = 1.initBigInt
sum = 0.initBigInt
n = 1.initBigInt
while true:
sum += fact
fact *= n
n += 1
yield sum
echo "first 11:\n "
for i in lfact().slice(last = 10):
echo " ", i
echo "20 through 110 (inclusive) by tens:"
for i in lfact().slice(20, 110, 10):
echo " ", i
echo "Digits in 1,000 through 10,000 (inclusive) by thousands:"
for i in lfact().slice(1_000, 10_000, 1_000):
echo " ", ($i).len

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@ -0,0 +1 @@
: leftFact | i | 0 1 rot loop: i [ tuck + swap i * ] drop ;

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@ -0,0 +1,4 @@
lf(n)=sum(k=0,n-1,k!);
apply(lf, [0..10])
apply(lf, 10*[2..11])
forstep(n=1000,1e4,1000,print1(#digits(lf(n))", "))

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@ -0,0 +1,23 @@
lf: procedure (n) returns (fixed decimal (31) );
declare n fixed binary;
declare (s, f) fixed (31);
declare (i, j) fixed;
s = 0;
do i = n-1 to 0 by -1;
f = 1;
do j = i to 1 by -1;
f = f * j;
end;
s = s + f;
end;
return (s);
end lf;
declare n fixed binary;
do n = 0 to 10, 20 to 30;
put skip list ('Left factorial of ' || n || '=' || lf(n) );
end;
end left_factorials;

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@ -0,0 +1,23 @@
#!perl
use 5.010;
use strict;
use warnings;
use bigint;
sub leftfact {
my ($n) = @_;
state $cached = 0;
state $factorial = 1;
state $leftfact = 0;
if( $n < $cached ) {
($cached, $factorial, $leftfact) = (0, 1, 0);
}
while( $n > $cached ) {
$leftfact += $factorial;
$factorial *= ++$cached;
}
return $leftfact;
}
printf "!%d = %s\n", $_, leftfact($_) for 0 .. 10, map $_*10, 2..11;
printf "!%d has %d digits.\n", $_, length leftfact($_) for map $_*1000, 1..10;

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@ -0,0 +1,32 @@
(phixonline)-->
<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>
<span style="color: #008080;">include</span> <span style="color: #004080;">mpfr</span><span style="color: #0000FF;">.</span><span style="color: #000000;">e</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">lf_list</span>
<span style="color: #008080;">procedure</span> <span style="color: #000000;">init</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">mpz</span> <span style="color: #000000;">f</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">mpz_init</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">lf_list</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #000000;">f</span><span style="color: #0000FF;">,</span><span style="color: #000000;">n</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">n</span> <span style="color: #008080;">do</span>
<span style="color: #000000;">f</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">mpz_init_set</span><span style="color: #0000FF;">(</span><span style="color: #000000;">f</span><span style="color: #0000FF;">)</span>
<span style="color: #7060A8;">mpz_mul_si</span><span style="color: #0000FF;">(</span><span style="color: #000000;">f</span><span style="color: #0000FF;">,</span><span style="color: #000000;">f</span><span style="color: #0000FF;">,</span><span style="color: #000000;">i</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">lf_list</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">f</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">lf</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">bool</span> <span style="color: #000000;">len</span><span style="color: #0000FF;">=</span><span style="color: #004600;">false</span><span style="color: #0000FF;">)</span>
<span style="color: #000080;font-style:italic;">-- Returns left factorial of n, or it's length, as a string</span>
<span style="color: #004080;">mpz</span> <span style="color: #000000;">sumf</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">mpz_init</span><span style="color: #0000FF;">(</span><span style="color: #000000;">0</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">k</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">n</span> <span style="color: #008080;">do</span> <span style="color: #7060A8;">mpz_add</span><span style="color: #0000FF;">(</span><span style="color: #000000;">sumf</span><span style="color: #0000FF;">,</span><span style="color: #000000;">sumf</span><span style="color: #0000FF;">,</span><span style="color: #000000;">lf_list</span><span style="color: #0000FF;">[</span><span style="color: #000000;">k</span><span style="color: #0000FF;">])</span> <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">return</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">len</span><span style="color: #0000FF;">?</span><span style="color: #7060A8;">sprintf</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"%d"</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">mpz_sizeinbase</span><span style="color: #0000FF;">(</span><span style="color: #000000;">sumf</span><span style="color: #0000FF;">,</span><span style="color: #000000;">10</span><span style="color: #0000FF;">))</span>
<span style="color: #0000FF;">:</span><span style="color: #7060A8;">shorten</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">mpz_get_str</span><span style="color: #0000FF;">(</span><span style="color: #000000;">sumf</span><span style="color: #0000FF;">)))</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<span style="color: #000080;font-style:italic;">-- Main procedure</span>
<span style="color: #004080;">atom</span> <span style="color: #000000;">t0</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">time</span><span style="color: #0000FF;">()</span>
<span style="color: #000000;">init</span><span style="color: #0000FF;">(</span><span style="color: #000000;">10000</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">0</span> <span style="color: #008080;">to</span> <span style="color: #000000;">10</span> <span style="color: #008080;">do</span> <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"!%d = %s\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">i</span><span style="color: #0000FF;">,</span><span style="color: #000000;">lf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">i</span><span style="color: #0000FF;">)})</span> <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">20</span> <span style="color: #008080;">to</span> <span style="color: #000000;">110</span> <span style="color: #008080;">by</span> <span style="color: #000000;">10</span> <span style="color: #008080;">do</span> <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"!%d = %s\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">i</span><span style="color: #0000FF;">,</span><span style="color: #000000;">lf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">i</span><span style="color: #0000FF;">)})</span> <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1000</span> <span style="color: #008080;">to</span> <span style="color: #000000;">10000</span> <span style="color: #008080;">by</span> <span style="color: #000000;">1000</span> <span style="color: #008080;">do</span> <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"!%d contains %s digits\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">i</span><span style="color: #0000FF;">,</span><span style="color: #000000;">lf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">i</span><span style="color: #0000FF;">,</span><span style="color: #004600;">true</span><span style="color: #0000FF;">)})</span> <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"complete (%3.2fs)\n"</span><span style="color: #0000FF;">,{</span><span style="color: #7060A8;">time</span><span style="color: #0000FF;">()-</span><span style="color: #000000;">t0</span><span style="color: #0000FF;">})</span>
<!--

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@ -0,0 +1,17 @@
(de n! (N)
(cache '(NIL) N
(if (> 2 N) 1
(* N (n! (dec N))))))
(de !n (Num)
(if (= Num 0) 1
(sum n! (range 0 (dec Num)))))
(de pril (List) (mapcar 'println List))
(prinl "0-10")
(pril (mapcar '!n (range 0 10)))
(prinl "20 - 110")
(pril (mapcar '!n (range 20 110 10)))
(prinl "length of 1000 - 10000")
(pril (mapcar 'length (mapcar '!n (range 1000 10000 1000))))

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@ -0,0 +1,34 @@
0-10
1
1
2
4
10
34
154
874
5914
46234
409114
20 - 110
128425485935180314
9157958657951075573395300940314
20935051082417771847631371547939998232420940314
620960027832821612639424806694551108812720525606160920420940314
141074930726669571000530822087000522211656242116439949000980378746128920420940314
173639511802987526699717162409282876065556519849603157850853034644815111221599509216528920420940314
906089587987695346534516804650290637694024830011956365184327674619752094289696314882008531991840922336528920420940314
16695570072624210767034167688394623360733515163575864136345910335924039962404869510225723072235842668787507993136908442336528920420940314
942786239765826579160595268206839381354754349601050974345395410407078230249590414458830117442618180732911203520208889371641659121356556442336528920420940314
145722981061585297004706728001906071948635199234860720988658042536179281328615541936083296163475394237524337422204397431927131629058103519228197429698252556442336528920420940314
1000 - 10000
2565
5733
9128
12670
16322
20062
23875
27749
31678
35656

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@ -0,0 +1,26 @@
function left-factorial ([BigInt]$n) {
[BigInt]$k, [BigInt]$fact = ([BigInt]::Zero), ([BigInt]::One)
[BigInt]$lfact = ([BigInt]::Zero)
while($k -lt $n){
if($k -gt ([BigInt]::Zero)) {
$fact = [BigInt]::Multiply($fact, $k)
$lfact = [BigInt]::Add($lfact, $fact)
} else {
$lfact = ([BigInt]::One)
}
$k = [BigInt]::Add($k, [BigInt]::One)
}
$lfact
}
0..9 | foreach{
"!$_ = $(left-factorial $_)"
}
for($i = 10; $i -le 110; $i += 10) {
"!$i = $(left-factorial $i)"
}
for($i = 1000; $i -le 10000; $i += 1000) {
$digits = [BigInt]::Log10($(left-factorial $i))
$digits = [Math]::Floor($digits) + 1
if($digits -gt 1) {"!$i has $digits digits"}
else {"!$i has $digits digit"}
}

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@ -0,0 +1,22 @@
leftfact(N):-
leftfact(N, 0, 0, 1).
leftfact(N, N, _, _):-
!.
leftfact(N, M, L, F):-
((M =< 10 ; (M =< 110, 0 is M mod 10)) ->
writef("!%w = %w\n", [M, L])
;
(0 is M mod 1000 ->
number_string(L, S),
string_length(S, Len),
writef("length of !%w is %w\n", [M, Len])
;
true)),
L1 is L + F,
M1 is M + 1,
F1 is F * M1,
leftfact(N, M1, L1, F1).
main:-
leftfact(10001).

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from itertools import islice
def lfact():
yield 0
fact, summ, n = 1, 0, 1
while 1:
fact, summ, n = fact*n, summ + fact, n + 1
yield summ
print('first 11:\n %r' % [lf for i, lf in zip(range(11), lfact())])
print('20 through 110 (inclusive) by tens:')
for lf in islice(lfact(), 20, 111, 10):
print(lf)
print('Digits in 1,000 through 10,000 (inclusive) by thousands:\n %r'
% [len(str(lf)) for lf in islice(lfact(), 1000, 10001, 1000)] )

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@ -0,0 +1,92 @@
'''Left factorials'''
from itertools import (accumulate, chain, count, islice)
from operator import (mul, add)
# leftFact :: [Integer]
def leftFact():
'''Left factorial series defined in terms
of the factorial series.
'''
return accumulate(
chain([0], fact()), add
)
# fact :: [Integer]
def fact():
'''The factorial series.
'''
return accumulate(
chain([1], count(1)), mul
)
# ------------------------- TEST -------------------------
# main :: IO ()
def main():
'''Tests'''
print(
'Terms 0 thru 10 inclusive:\n %r'
% take(11)(leftFact())
)
print('\nTerms 20 thru 110 (inclusive) by tens:')
for x in takeFromThenTo(20)(30)(110)(leftFact()):
print(x)
print(
'\n\nDigit counts for terms 1k through 10k (inclusive) by k:\n %r'
% list(map(
compose(len)(str),
takeFromThenTo(1000)(2000)(10000)(
leftFact()
)
))
)
# ----------------------- GENERIC ------------------------
# compose (<<<) :: (b -> c) -> (a -> b) -> a -> c
def compose(g):
'''Function composition.'''
return lambda f: lambda x: g(f(x))
# scanl :: (b -> a -> b) -> b -> [a] -> [b]
def scanl(f):
'''scanl is like reduce, but defines a succession of
intermediate values, building from the left.
'''
def go(a):
def g(xs):
return accumulate(chain([a], xs), f)
return g
return go
# take :: Int -> [a] -> [a]
# take :: Int -> String -> String
def take(n):
'''The prefix of xs of length n,
or xs itself if n > length xs'''
return lambda xs: (
xs[0:n]
if isinstance(xs, list)
else list(islice(xs, n))
)
# takeFromThenTo :: Int -> Int -> Int -> [a] -> [a]
def takeFromThenTo(a):
'''Values drawn from a series betweens positions a and b
at intervals of size z'''
return lambda b: lambda z: lambda xs: islice(
xs, a, 1 + z, b - a
)
if __name__ == '__main__':
main()

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[ 1 swap times [ i 1+ * ] ] is ! ( n --> n )
[ 0 swap times [ i ! + ] ] is !n ( n --> n )
say "First 11 left factorials:" cr
11 times [ i^ !n echo sp ] cr
cr
say "20 through 110 (inclusive) by tens:" cr
10 times [ i^ 2 + 10 * !n echo cr ]
cr
say "Digits in 1,000 through 10,000 by thousands:" cr
10 times [ i^ 1+ 1000 * !n number$ size echo cr ]
cr

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library(gmp)
left_factorial <- function(n) {
if (n == 0) return(0)
result <- as.bigz(0)
adder <- as.bigz(1)
for (k in 1:n) {
result <- result + adder
adder <- adder * k
}
result
}
digit_count <- function(n) {
nchar(as.character(n))
}
for (n in 0:10) {
cat("!",n," = ",sep = "")
cat(as.character(left_factorial(n)))
cat("\n")
}
for (n in seq(20,110,10)) {
cat("!",n," = ",sep = "")
cat(as.character(left_factorial(n)))
cat("\n")
}
for (n in seq(1000,10000,1000)) {
cat("!",n," has ",digit_count(left_factorial(n))," digits\n", sep = "")
}

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library(gmp)
leftFact <- function(numbs)
{
#As we will never actually use the numeric values of our outputs, we will
#immediately coerce them to characters. For technical reasons to do with
#nchar misbehaving, this also makes task 3 much easier.
#As task 1 will demonstrate, the n=0 special case is covered.
sapply(numbs, function(n) as.character(sum(factorialZ(seq_len(n)-1))))
}
printer <- function(inputs) print(data.frame(Value = leftFact(inputs), row.names = paste0("!", inputs)))
#Task 1
printer(0:10)
#Task 2
printer(seq(20, 110, by = 10))
#Task 3
inputs<-seq(1000, 10000, by = 1000)
print(data.frame(Digits = sapply(leftFact(inputs), nchar), row.names = paste0("!", inputs)))

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/*REXX program computes/display the left factorial (or its dec. width) of N (or a range)*/
parse arg bot top inc . /*obtain optional arguments from the CL*/
if bot=='' | bot=="," then bot= 1 /*Not specified: Then use the default.*/
if top=='' | top=="," then top= bot /* " " " " " " */
if inc='' | inc=="," then inc= 1 /* " " " " " " */
tell= bot<0 /*if BOT < 0, only show # of digits. */
bot= abs(bot) /*use the │bot│ for the DO loop. */
w= length(top) /*width of the largest number request. */
do j=bot to top by inc /*traipse through the numbers requested*/
if tell then say 'left ! of ' right(j,w) " ───► " length(L!(j)) ' digits'
else say 'left ! of ' right(j,w) " ───► " L!(j)
end /*j*/ /* [↑] show either L! or # of digits*/
exit 0 /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
L!: procedure; parse arg x .; if x<3 then return x; $= 4; != 2 /*some shortcuts.*/
do #=3 to x-1; != ! * # /*compute L! for all numbers ─── ► X.*/
if pos(., !)\==0 then numeric digits digits() * 3 % 2 /*bump dec. digs.*/
$= $ + ! /*add the factorial ───► L! sum. */
end /*#*/ /* [↑] handles gihugeic numbers. */
return $ /*return the sum (L!) to the invoker.*/

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@ -0,0 +1,17 @@
#lang racket
(define ! (let ((rv# (make-hash))) (λ (n) (hash-ref! rv# n (λ () (if (= n 0) 1 (* n (! (- n 1)))))))))
(define (!n n)
;; note that in-range n is from 0 to n-1 inclusive
(for/sum ((k (in-range n))) (! k)))
(define (dnl. s) (for-each displayln s))
(dnl
"Display the left factorials for:"
"zero through ten (inclusive)"
(pretty-format (for/list ((i (in-range 0 (add1 10)))) (!n i)))
"20 through 110 (inclusive) by tens"
(pretty-format (for/list ((i (in-range 20 (add1 110) 10))) (!n i)))
"Display the length (in decimal digits) of the left factorials for:"
"1,000, 2,000 through 10,000 (inclusive), by thousands."
(pretty-format (for/list ((i (in-range 1000 10001 1000))) (add1 (order-of-magnitude (!n i))))))

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@ -0,0 +1,6 @@
sub prefix:<!> ($k) { (constant l = 0, |[\+] 1, (|[\*] 1..*))[$k] }
$ = !10000; # Pre-initialize
.say for ( 0 10, 20 110 ).hyper(:4batch).map: { sprintf "!%d = %s", $_, !$_ };
.say for (1000, 2000 10000).hyper(:4batch).map: { sprintf "!%d has %d digits.", $_, chars !$_ };

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@ -0,0 +1,6 @@
constant leftfact = 0, |[\+] 1, (|[\*] 1..*);
$ = leftfact[10000]; # Pre-initialize
.say for ( 0 10, 20 110 ).hyper(:4batch).map: { sprintf "!%d = %s", $_, leftfact[$_] };
.say for (1000, 2000 10000).hyper(:4batch).map: { sprintf "!%d has %d digits.", $_, chars leftfact[$_] };

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a = leftFact(0,10,1)
see "" + a + nl
func leftFact f,t,s
see "------ From " + f + " --To -> " + t +" Step " + s + " -------" + nl
for i = f to t step s
leftFact = 1
fct = 1
for j = 1 to i - 1
fct = fct * j
leftFact = leftFact + fct
next
if i >= 1000 see "" + i + " " + len(string(leftFact)) + " digits" + nl
else see "" + i + " " + leftFact + nl ok
next

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@ -0,0 +1,8 @@
left_fact = Enumerator.new do |y|
f, lf = 1, 0
1.step do |n|
y << lf #yield left_factorial
lf += f
f *= n
end
end

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@ -0,0 +1,12 @@
tens = 20.step(110, 10)
thousands = 1000.step(10_000, 1000)
10001.times do |n|
lf = left_fact.next
case n
when 0..10, *tens
puts "!#{n} = #{lf}"
when *thousands
puts "!#{n} has #{lf.to_s.size} digits"
end
end

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a = lftFct(0,10,1)
a = lftFct(20,110,10)
a = lftFct(1000,10000,1000)
function lftFct(f,t,s)
print :print "------ From ";f;" --To-> ";t;" Step ";s;" -------"
for i = f to t step s
lftFct = 1
fct = 1
for j = 1 to i-1
fct = fct * j
lftFct = lftFct + fct
next j
if i >= 1000 then
print i;" ";len(str$(lftFct));" "digits"
else
print i;" ";lftFct
end if
next i
end function

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@ -0,0 +1,123 @@
#[cfg(target_pointer_width = "64")]
type USingle = u32;
#[cfg(target_pointer_width = "64")]
type UDouble = u64;
#[cfg(target_pointer_width = "64")]
const WORD_LEN: i32 = 32;
#[cfg(not(target_pointer_width = "64"))]
type USingle = u16;
#[cfg(not(target_pointer_width = "64"))]
type UDouble = u32;
#[cfg(not(target_pointer_width = "64"))]
const WORD_LEN: i32 = 16;
use std::cmp;
#[derive(Debug,Clone)]
struct BigNum {
// rep_.size() == 0 if and only if the value is zero.
// Otherwise, the word rep_[0] keeps the least significant bits.
rep_: Vec<USingle>,
}
impl BigNum {
pub fn new(n: USingle) -> BigNum {
let mut result = BigNum { rep_: vec![] };
if n > 0 { result.rep_.push(n); }
result
}
pub fn equals(&self, n: USingle) -> bool {
if n == 0 { return self.rep_.is_empty() }
if self.rep_.len() > 1 { return false }
self.rep_[0] == n
}
pub fn add_big(&self, addend: &BigNum) -> BigNum {
let mut result = BigNum::new(0);
let mut sum = 0 as UDouble;
let sz1 = self.rep_.len();
let sz2 = addend.rep_.len();
for i in 0..cmp::max(sz1, sz2) {
if i < sz1 { sum += self.rep_[i] as UDouble }
if i < sz2 { sum += addend.rep_[i] as UDouble }
result.rep_.push(sum as USingle);
sum >>= WORD_LEN;
}
if sum > 0 { result.rep_.push(sum as USingle) }
result
}
pub fn multiply(&self, factor: USingle) -> BigNum {
let mut result = BigNum::new(0);
let mut product = 0 as UDouble;
for i in 0..self.rep_.len() {
product += self.rep_[i] as UDouble * factor as UDouble;
result.rep_.push(product as USingle);
product >>= WORD_LEN;
}
if product > 0 {
result.rep_.push(product as USingle);
}
result
}
pub fn divide(&self, divisor: USingle, quotient: &mut BigNum,
remainder: &mut USingle) {
quotient.rep_.truncate(0);
let mut dividend: UDouble;
*remainder = 0;
for i in 0..self.rep_.len() {
let j = self.rep_.len() - 1 - i;
dividend = ((*remainder as UDouble) << WORD_LEN)
+ self.rep_[j] as UDouble;
let quo = (dividend / divisor as UDouble) as USingle;
*remainder = (dividend % divisor as UDouble) as USingle;
if quo > 0 || j < self.rep_.len() - 1 {
quotient.rep_.push(quo);
}
}
quotient.rep_.reverse();
}
fn to_string(&self) -> String {
let mut rep = String::new();
let mut dividend = (*self).clone();
let mut remainder = 0 as USingle;
let mut quotient = BigNum::new(0);
loop {
dividend.divide(10, &mut quotient, &mut remainder);
rep.push(('0' as USingle + remainder) as u8 as char);
if quotient.equals(0) { break; }
dividend = quotient.clone();
}
rep.chars().rev().collect::<String>()
}
}
use std::fmt;
impl fmt::Display for BigNum {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{}", self.to_string())
}
}
fn lfact(n: USingle) -> BigNum {
let mut result = BigNum::new(0);
let mut f = BigNum::new(1);
for k in 1 as USingle..n + 1 {
result = result.add_big(&f);
f = f.multiply(k);
}
result
}
fn main() {
for i in 0..11 {
println!("!{} = {}", i, lfact(i));
}
for i in 2..12 {
let j = i * 10;
println!("!{} = {}", j, lfact(j));
}
for i in 1..11 {
let j = i * 1000;
println!("!{} has {} digits.", j, lfact(j).to_string().len());
}
}

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// [dependencies]
// rug = "1.9"
fn left_factorials() -> impl std::iter::Iterator<Item = rug::Integer> {
use rug::Integer;
let mut factorial = Integer::from(1);
let mut next = Integer::from(0);
let mut n = 1;
std::iter::from_fn(move || {
let result = next.clone();
next += &factorial;
factorial *= n;
n += 1;
Some(result)
})
}
fn main() {
let mut lf = left_factorials().take(10001).enumerate();
println!("Left factorials 0 through 10:");
for (i, n) in lf.by_ref().take(11) {
println!("!{} = {}", i, n);
}
println!("Left factorials 20 through 110, by tens:");
for (i, n) in lf.by_ref().take(100).skip(9).step_by(10) {
println!("!{} = {}", i, n);
}
println!("Lengths of left factorials 1000 through 10000, by thousands:");
for (i, n) in lf.skip(1000 - 111).step_by(1000) {
println!("length of !{} = {}", i, n.to_string().len());
}
}

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object LeftFactorial extends App {
// this part isn't really necessary, it just shows off Scala's ability
// to match the mathematical syntax: !n
implicit class RichInt(n:Int) {
def unary_!() = factorial.take(n).sum
}
val factorial: Stream[BigInt] = 1 #:: factorial.zip(Stream.from(1)).map(n => n._2 * factorial(n._2 - 1))
for (n <- (0 to 10) ++
(20 to 110 by 10);
value = !n) {
println(s"!${n} = ${value}")
}
for (n <- 1000 to 10000 by 1000;
length = (!n).toString.length) {
println(s"length !${n} = ${length}")
}
}

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(import (scheme base) ;; library imports in R7RS style
(scheme write)
(srfi 1 lists))
(define (factorial n)
(fold * 1 (iota n 1)))
(define (left-factorial n)
(fold + 0 (map factorial (iota n))))
(define (show i r) ; to pretty print the results
(display "!") (display i) (display " ") (display r) (newline))
;; show left factorials for zero through ten (inclusive)
(for-each
(lambda (i) (show i (left-factorial i)))
(iota 11))
;; show left factorials for 20 through 110 (inclusive) by tens
(for-each
(lambda (i) (show i (left-factorial i)))
(iota 10 20 10))
;; number of digits in 1000 through 10000 by thousands:
(for-each
(lambda (i) (show i (string-length (number->string (left-factorial i)))))
(iota 10 1000 1000))

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$ include "seed7_05.s7i";
include "bigint.s7i";
const func bigInteger: leftFact (in integer: n) is func
result
var bigInteger: leftFact is 0_;
local
var bigInteger: factorial is 1_;
var integer: i is 0;
begin
for i range 1 to n do
leftFact +:= factorial;
factorial *:= bigInteger conv i;
end for;
end func;
const proc: main is func
local
var integer: n is 0;
begin
writeln("First 11 left factorials:");
for n range 0 to 10 do
write(" " <& leftFact(n));
end for;
writeln;
writeln("20 through 110 (inclusive) by tens:");
for n range 20 to 110 step 10 do
writeln(leftFact(n));
end for;
writeln;
writeln("Digits in 1,000 through 10,000 by thousands:");
for n range 1000 to 10000 step 1000 do
writeln(length(str(leftFact(n))));
end for;
writeln;
end func;

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say 20.of { .left_factorial }

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func left_factorial(n) {
^n -> sum { _! }
}

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func left_factorial(n) {
^n -> reduce({ |a,b| a + b! }, 0)
}

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func left_factorial(n) {
static cached = 0
static factorial = 1
static leftfact = 0
if (n < cached) {
cached = 0
factorial = 1
leftfact = 0
}
while (n > cached) {
leftfact += factorial
factorial *= ++cached
}
leftfact
}

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for n in (0..10, 20..110 `by` 10) {
printf("!%d = %s\n", n, left_factorial(n))
}
for n in (1000..10000 `by` 1000) {
printf("!%d has %d digits.\n", n, left_factorial(n).len)
}

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(* reuse earlier factorial calculations in dfac, apply to listed arguments in cumlfac *)
(* example: left factorial n, is #3 (dfac (0,n-1,1,1) ) *)
(* output list contains (number, factorial, left factorial) *)
(* tested in PolyML *)
val store = ref 0;
val rec dfac = fn
(from,to,acc,cm) => if from = to then (from,acc,cm) else (store:=(from+1)*acc;dfac (from+1,to,!store,!store+cm ) );
val rec cumlfac = fn
(x::y::rm) => x :: cumlfac ( dfac (#1 x, #1 y, #2 x, #3 x) :: rm ) |
rm =>rm ;
val arguments = List.tabulate (10,fn 0=>(0,1,1)|i=>(i,0,0)) @
List.tabulate (10,fn i=> (10*i+19,0,0) ) @
List.tabulate ( 10,fn i=> (1000*i+999,0,0));
val result = (~1,0,0)::(cumlfac arguments);
(* done *)
(* display: *)
List.app (fn triple :int*int*int =>
print(Int.toString (1+ #1 triple ) ^ " : " ^ Int.fmt StringCvt.DEC (#3 triple ) ^" \n" )
) (List.take(result,21) ) ;
List.app (fn triple :int*int*int =>
print( Int.toString (1+ #1 triple ) ^ " : " ^ Int.toString (size(Int.toString (#3 triple ))) ^" \n" ) ) (List.drop(result,21) );

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import BigInt
func factorial<T: BinaryInteger>(_ n: T) -> T {
guard n != 0 else {
return 1
}
return stride(from: n, to: 0, by: -1).reduce(1, *)
}
prefix func ! <T: BinaryInteger>(n: T) -> T {
guard n != 0 else {
return 0
}
return stride(from: 0, to: n, by: 1).lazy.map(factorial).reduce(0, +)
}
for i in 0...10 {
print("!\(i) = \(!i)")
}
print()
for i in stride(from: BigInt(20), through: 110, by: 10) {
print("!\(i) = \(!i)")
}
print()
print("!1000 = \((!BigInt(1000)).description.count) digit number")
print()
for i in stride(from: BigInt(2000), through: 10_000, by: 1000) {
print("!\(i) = \((!i).description.count) digit number")
}

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proc leftfact {n} {
set s 0
for {set i [set f 1]} {$i <= $n} {incr i} {
incr s $f
set f [expr {$f * $i}]
}
return $s
}
for {set i 0} {$i <= 110} {incr i [expr {$i>9?10:1}]} {
puts "!$i = [leftfact $i]"
}
for {set i 1000} {$i <= 10000} {incr i 1000} {
puts "!$i has [string length [leftfact $i]] digits"
}

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import "/fmt" for Fmt
import "/big" for BigInt
var lfacts = List.filled(12, BigInt.zero)
var lfact = BigInt.one
var sum = BigInt.zero
for (i in 1..10) {
sum = sum + lfact
lfacts[i] = sum
lfact = lfact * i
}
System.print("Left factorials from 0 to 10:")
for (i in 0..10) System.write(" %(lfacts[i])")
for (i in 11..110) {
sum = sum + lfact
if (i%10 == 0) lfacts[i/10] = sum
lfact = lfact * i
}
System.print("\n\nLeft factorials from 20 to 110 by tens:")
for (i in 2..11) Fmt.print(" !$-3d -> $s", i * 10, lfacts[i])
for (i in 111..10000) {
sum = sum + lfact
if (i%1000 == 0) lfacts[i/1000] = sum
lfact = lfact * i
}
System.print("\nLengths of left factorals from 1000 to 10000 by thousands:")
for (i in 1..10) Fmt.print(" !$-5d -> $5s", i * 1000, lfacts[i].toString.count)

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var BN=Import("zklBigNum");
fcn leftFact(n){
[1..n].reduce(fcn(p,n,rf){ p+=rf.value; rf.set(rf.value*n); p },
BN(0),Ref(BN(1)));
}

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println("First 11 left factorials:\n", [0..10].apply(leftFact));
lfs:=[20..111,10].apply(leftFact);
println(("\n20 through 110 (inclusive) by tens:\n" +
"%d\n"*lfs.len()).fmt(lfs.xplode()));
println("Digits in 1,000 through 10,000 by thousands:\n",
[0d1_000..0d10_000, 1000].pump(List,fcn(n){leftFact(n).toString().len()}));