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Ingy döt Net 2023-07-01 11:58:00 -04:00
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---
from: http://rosettacode.org/wiki/Mian-Chowla_sequence

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The [[wp:MianChowla sequence|MianChowla sequence]] is an integer sequence defined recursively.
MianChowla is an infinite instance of a [[wp:Sidon sequence|Sidon sequence]], and belongs to the class known as B₂ sequences.
The sequence starts with:
::<span style="font-style:italic;font-weight:bold;font-size:125%;">a<sub>1</sub> = 1</span>
then for <span style="font-style:italic;font-weight:bold;font-size:125%;padding:.3em;">n > 1,</span> <span style="font-style:italic;font-weight:bold;font-size:125%;padding:.3em;">a<sub>n</sub></span> is the smallest positive integer such that every pairwise sum
::<span style="font-style:italic;font-weight:bold;font-size:125%;">a<sub>i</sub> + a<sub>j</sub>
is distinct, for all <span style="font-style:italic;font-weight:bold;font-size:125%;">i</span> and <span style="font-style:italic;font-weight:bold;font-size:125%;">j</span> less than or equal to <span style="font-style:italic;font-weight:bold;font-size:125%;">n</span>.
;The Task:
:* Find and display, here, on this page the first 30 terms of the MianChowla sequence.
:* Find and display, here, on this page the 91st through 100th terms of the MianChowla sequence.
Demonstrating working through the first few terms longhand:
::<span style="font-style:italic;font-weight:bold;font-size:125%;">a<sub>1</sub> = 1</span>
::<span style="font-weight:bold;">1 + 1 = 2</span>
Speculatively try <span style="font-style:italic;font-weight:bold;font-size:125%;padding:.3em;">a<sub>2</sub> = 2</span>
::<span style="font-weight:bold;">1 + 1 = 2</span>
::<span style="font-weight:bold;">1 + 2 = 3</span>
::<span style="font-weight:bold;">2 + 2 = 4</span>
There are no repeated sums so '''2''' is the next number in the sequence.
Speculatively try <span style="font-style:italic;font-weight:bold;font-size:125%;padding:.3em;">a<sub>3</sub> = 3</span>
::<span style="font-weight:bold;">1 + 1 = 2</span>
::<span style="font-weight:bold;">1 + 2 = 3</span>
::<span style="font-weight:bold;">1 + 3 = <span style="background-color:yellow;">4</span></span>
::<span style="font-weight:bold;">2 + 2 = <span style="background-color:yellow;">4</span></span>
::<span style="font-weight:bold;">2 + 3 = 5</span>
::<span style="font-weight:bold;">3 + 3 = 6</span>
Sum of '''4''' is repeated so '''3''' is rejected.
Speculatively try <span style="font-style:italic;font-weight:bold;font-size:125%;padding:.3em;">a<sub>3</sub> = 4</span>
::<span style="font-weight:bold;">1 + 1 = 2</span>
::<span style="font-weight:bold;">1 + 2 = 3</span>
::<span style="font-weight:bold;">1 + 4 = 5</span>
::<span style="font-weight:bold;">2 + 2 = 4</span>
::<span style="font-weight:bold;">2 + 4 = 6</span>
::<span style="font-weight:bold;">4 + 4 = 8</span>
There are no repeated sums so '''4''' is the next number in the sequence.
And so on...
;See also:
:* [[oeis:A005282|OEIS:A005282 Mian-Chowla sequence]]

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F contains(sums, s, ss)
L(i) 0 .< ss
I sums[i] == s
R 1B
R 0B
F mian_chowla()
V n = 100
V mc = [0] * n
mc[0] = 1
V sums = [0] * ((n * (n + 1)) >> 1)
sums[0] = 2
V ss = 1
L(i) 1 .< n
V le = ss
V j = mc[i - 1] + 1
L
mc[i] = j
V nxtJ = 0B
L(k) 0 .. i
V sum = mc[k] + j
I contains(sums, sum, ss)
ss = le
nxtJ = 1B
L.break
sums[ss] = sum
ss++
I !nxtJ
L.break
j++
R mc
print(The first 30 terms of the Mian-Chowla sequence are:)
V mc = mian_chowla()
print_elements(mc[0.<30])
print()
print(Terms 91 to 100 of the Mian-Chowla sequence are:)
print_elements(mc[90..])

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# Find Mian-Chowla numbers: an
where: ai = 1,
and: an = smallest integer such that ai + aj is unique
for all i, j in 1 .. n && i <= j
#
BEGIN
INT max mc = 100;
[ max mc ]INT mc;
INT curr size := 0; # initial size of the array #
INT size increment = 10 000; # size to increase the array by #
REF[]BOOL is sum := HEAP[ 1 : 0 ]BOOL;
INT mc count := 1;
FOR i WHILE mc count <= max mc DO
# assume i will be part of the sequence #
mc[ mc count ] := i;
# check the sums #
IF ( 2 * i ) > curr size THEN
# the is sum array is too small - make a larger one #
REF[]BOOL new sum = HEAP[ curr size + size increment ]BOOL;
new sum[ 1 : curr size ] := is sum;
FOR n TO size increment DO new sum[ curr size + n ] := FALSE OD;
curr size +:= size increment;
is sum := new sum
FI;
BOOL is unique := TRUE;
FOR mc pos TO mc count WHILE is unique := NOT is sum[ i + mc[ mc pos ] ] DO SKIP OD;
IF is unique THEN
# i is a sequence element - store the sums #
FOR k TO mc count DO is sum[ i + mc[ k ] ] := TRUE OD;
mc count +:= 1
FI
OD;
# print parts of the sequence #
print( ( "Mian Chowla sequence elements 1..30:", newline ) );
FOR i TO 30 DO print( ( " ", whole( mc[ i ], 0 ) ) ) OD;
print( ( newline ) );
print( ( "Mian Chowla sequence elements 91..100:", newline ) );
FOR i FROM 91 TO 100 DO print( ( " ", whole( mc[ i ], 0 ) ) ) OD
END

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# Find Mian-Chowla numbers: an
# where: ai = 1,
# and: an = smallest integer such that ai + aj is unique
# for all i, j in 1 .. n && i <= j
#
BEGIN \
{
FALSE = 0;
TRUE = 1;
mcCount = 1;
for( i = 1; mcCount <= 100; i ++ )
{
# assume i will be part of the sequence
mc[ mcCount ] = i;
# check the sums
isUnique = TRUE;
for( mcPos = 1; mcPos <= mcCount && isUnique; mcPos ++ )
{
isUnique = ! ( ( i + mc[ mcPos ] ) in isSum );
} # for j
if( isUnique )
{
# i is a sequence element - store the sums
for( k = 1; k <= mcCount; k ++ )
{
isSum[ i + mc[ k ] ] = TRUE;
} # for k
mcCount ++;
} # if isUnique
} # for i
# print the sequence
printf( "Mian Chowla sequence elements 1..30:\n" );
for( i = 1; i <= 30; i ++ )
{
printf( " %d", mc[ i ] );
} # for i
printf( "\n" );
printf( "Mian Chowla sequence elements 91..100:\n" );
for( i = 91; i <= 100; i ++ )
{
printf( " %d", mc[ i ] );
} # for i
printf( "\n" );
} # BEGIN

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# helper functions
#
# determine if a list is empty or not
function isEmpty(a) { for (ii in a) return 0; return 1 }
# list concatination
function concat(a, b) { for (cc in b) a[cc] = cc }
BEGIN \
{
mc[0] = 1; sums[2] = 0; # initialize lists
for ( i = 1; i < 100; i ++ ) # iterate for each item in result
{
for ( j = mc[i-1]+1; ; j ++ ) # iterate thru trial values
{
mc[i] = j; # set trial value into result
for ( k = 0; k <= i; k ++ ) # test new iteration of sums
{
# test trial sum against old sums list
if ((sum = mc[k] + j) in sums)
{ # collision, so
delete ts; # toss out any accumulated items,
break; # and break out to the next j
}
ts[sum] = sum; # (else) accumulate to new sum list
} # for k
if ( isEmpty( ts ) ) # nothing to add,
continue; # so try next j
concat( sums, ts ); # combine new sums to old,
delete ts; # clear out the new,
break; # break out to next i
} # for j
} # for i
# print the sequence
ps = "Mian Chowla sequence elements %d..%d:\n";
for ( i = 0; i < 100; i ++ )
{
if ( i == 0 ) printf ps, 1, 30;
if ( i == 90 ) printf "\n\n" ps, 91, 100;
if ( i < 30 || i >= 90 ) printf "%d ", mc[ i ];
} # for i
print "\n"
} # BEGIN

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with Ada.Text_IO;
with Ada.Containers.Hashed_Sets;
procedure Mian_Chowla_Sequence
is
type Natural_Array is array(Positive range <>) of Natural;
function Hash(P : in Positive) return Ada.Containers.Hash_Type is
begin
return Ada.Containers.Hash_Type(P);
end Hash;
package Positive_Sets is new Ada.Containers.Hashed_Sets(Positive, Hash, "=");
function Mian_Chowla(N : in Positive) return Natural_Array
is
return_array : Natural_Array(1 .. N) := (others => 0);
nth : Positive := 1;
candidate : Positive := 1;
seen : Positive_Sets.Set;
begin
while nth <= N loop
declare
sums : Positive_Sets.Set;
terms : constant Natural_Array := return_array(1 .. nth-1) & candidate;
found : Boolean := False;
begin
for term of terms loop
if seen.Contains(term + candidate) then
found := True;
exit;
else
sums.Insert(term + candidate);
end if;
end loop;
if not found then
return_array(nth) := candidate;
seen.Union(sums);
nth := nth + 1;
end if;
candidate := candidate + 1;
end;
end loop;
return return_array;
end Mian_Chowla;
length : constant Positive := 100;
sequence : constant Natural_Array(1 .. length) := Mian_Chowla(length);
begin
Ada.Text_IO.Put_Line("Mian Chowla sequence first 30 terms :");
for term of sequence(1 .. 30) loop
Ada.Text_IO.Put(term'Img);
end loop;
Ada.Text_IO.New_Line;
Ada.Text_IO.Put_Line("Mian Chowla sequence terms 91 to 100 :");
for term of sequence(91 .. 100) loop
Ada.Text_IO.Put(term'Img);
end loop;
end Mian_Chowla_Sequence;

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mianChowla: function [n][
result: new [1]
sums: new [2]
candidate: 1
while [n > size result][
fit: false
'result ++ 0
while [not? fit][
candidate: candidate + 1
fit: true
result\[dec size result]: candidate
loop result 'val [
if contains? sums val + candidate [
fit: false
break
]
]
]
loop result 'val [
'sums ++ val + candidate
unique 'sums
]
]
return result
]
seq100: mianChowla 100
print "The first 30 terms of the Mian-Chowla sequence are:"
print slice seq100 0 29
print ""
print "Terms 91 to 100 of the sequence are:"
print slice seq100 90 99

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using namespace std;
#include <iostream>
#include <ctime>
#define n 100
#define nn ((n * (n + 1)) >> 1)
bool Contains(int lst[], int item, int size) {
for (int i = 0; i < size; i++) if (item == lst[i]) return true;
return false;
}
int * MianChowla()
{
static int mc[n]; mc[0] = 1;
int sums[nn]; sums[0] = 2;
int sum, le, ss = 1;
for (int i = 1; i < n; i++) {
le = ss;
for (int j = mc[i - 1] + 1; ; j++) {
mc[i] = j;
for (int k = 0; k <= i; k++) {
sum = mc[k] + j;
if (Contains(sums, sum, ss)) {
ss = le; goto nxtJ;
}
sums[ss++] = sum;
}
break;
nxtJ:;
}
}
return mc;
}
int main() {
clock_t st = clock(); int * mc; mc = MianChowla();
double et = ((double)(clock() - st)) / CLOCKS_PER_SEC;
cout << "The first 30 terms of the Mian-Chowla sequence are:\n";
for (int i = 0; i < 30; i++) { cout << mc[i] << ' '; }
cout << "\n\nTerms 91 to 100 of the Mian-Chowla sequence are:\n";
for (int i = 90; i < 100; i++) { cout << mc[i] << ' '; }
cout << "\n\nComputation time was " << et << " seconds.";
}

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using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
static class Program {
static int[] MianChowla(int n) {
int[] mc = new int[n - 1 + 1];
HashSet<int> sums = new HashSet<int>(), ts = new HashSet<int>();
int sum; mc[0] = 1; sums.Add(2);
for (int i = 1; i <= n - 1; i++) {
for (int j = mc[i - 1] + 1; ; j++) {
mc[i] = j;
for (int k = 0; k <= i; k++) {
sum = mc[k] + j;
if (sums.Contains(sum)) { ts.Clear(); break; }
ts.Add(sum);
}
if (ts.Count > 0) { sums.UnionWith(ts); break; }
}
}
return mc;
}
static void Main(string[] args)
{
const int n = 100; Stopwatch sw = new Stopwatch();
string str = " of the Mian-Chowla sequence are:\n";
sw.Start(); int[] mc = MianChowla(n); sw.Stop();
Console.Write("The first 30 terms{1}{2}{0}{0}Terms 91 to 100{1}{3}{0}{0}" +
"Computation time was {4}ms.{0}", '\n', str, string.Join(" ", mc.Take(30)),
string.Join(" ", mc.Skip(n - 10)), sw.ElapsedMilliseconds);
}
}

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#include <stdio.h>
#include <stdbool.h>
#include <time.h>
#define n 100
#define nn ((n * (n + 1)) >> 1)
bool Contains(int lst[], int item, int size) {
for (int i = size - 1; i >= 0; i--)
if (item == lst[i]) return true;
return false;
}
int * MianChowla()
{
static int mc[n]; mc[0] = 1;
int sums[nn]; sums[0] = 2;
int sum, le, ss = 1;
for (int i = 1; i < n; i++) {
le = ss;
for (int j = mc[i - 1] + 1; ; j++) {
mc[i] = j;
for (int k = 0; k <= i; k++) {
sum = mc[k] + j;
if (Contains(sums, sum, ss)) {
ss = le; goto nxtJ;
}
sums[ss++] = sum;
}
break;
nxtJ:;
}
}
return mc;
}
int main() {
clock_t st = clock(); int * mc; mc = MianChowla();
double et = ((double)(clock() - st)) / CLOCKS_PER_SEC;
printf("The first 30 terms of the Mian-Chowla sequence are:\n");
for (int i = 0; i < 30; i++) printf("%d ", mc[i]);
printf("\n\nTerms 91 to 100 of the Mian-Chowla sequence are:\n");
for (int i = 90; i < 100; i++) printf("%d ", mc[i]);
printf("\n\nComputation time was %f seconds.", et);
}

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#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <time.h>
// helper function for indicating memory used.
void approx(char* buf, double count)
{
const char* suffixes[] = { "Bytes", "KiB", "MiB" };
uint s = 0;
while (count >= 1024 && s < 3) { s++; count /= 1024; }
if (count - (double)((int)count) == 0.0)
sprintf(buf, "%d %s", (int)count, suffixes[s]);
else
sprintf(buf, "%.1f %s", count, suffixes[s]);
}
int main() {
int i, j, k, c = 0, n = 100, nn = 110;
int* mc = (int*) malloc((n) * sizeof(int));
bool* isSum = (bool*) calloc(nn, sizeof(bool));
char em[] = "unable to increase isSum array to %ld.";
if (n > 100) printf("Computing terms 1 to %d...\n", n);
clock_t st = clock();
for (i = 1; c < n; i++) {
mc[c] = i;
if (i + i > nn) {
bool* newIs = (bool*)realloc(isSum, (nn <<= 1) * sizeof(bool));
if (newIs == NULL) { printf(em, nn); return -1; }
isSum = newIs;
for (j = (nn >> 1); j < nn; j++) isSum[j] = false;
}
bool isUnique = true;
for (j = 0; (j < c) && isUnique; j++) isUnique = !isSum[i + mc[j]];
if (isUnique) {
for (k = 1; k <= c; k++) isSum[i + mc[k]] = true;
c++;
}
}
double et = 1e3 * ((double)(clock() - st)) / CLOCKS_PER_SEC;
free(isSum);
printf("The first 30 terms of the Mian-Chowla sequence are:\n");
for (i = 0; i < 30; i++) printf("%d ", mc[i]);
printf("\n\nTerms 91 to 100 of the Mian-Chowla sequence are:\n");
for (i = 90; i < 100; i++) printf("%d ", mc[i]);
if (c > 100) printf("\nTerm %d is: %d" ,c , mc[c - 1]);
free(mc);
char buf[100]; approx(buf, nn * sizeof(bool));
printf("\n\nComputation time was %6.3f ms. Allocation was %s.", et, buf);
}

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// Generate Mian-Chowla sequence. Nigel Galloway: March 23rd., 2019
let mC=let rec fN i g l=seq{
let a=(l*2)::[for i in i do yield i+l]@g
let b=[l+1..l*2]|>Seq.find(fun e->Seq.forall(fun g->(Seq.contains (g-e)>>not) i) a)
yield b; yield! fN (l::i) (a|>List.filter(fun n->n>b)) b}
seq{yield 1; yield! fN [] [] 1}

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mC |> Seq.take 30 |> Seq.iter(printf "%d ");printfn ""

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mC |> Seq.skip 90 |> Seq.take 10 |> Seq.iter(printf "%d ");printfn ""

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USING: fry hash-sets io kernel math prettyprint sequences sets ;
: next ( seq sums speculative -- seq' sums' speculative' )
dup reach [ + ] with map over dup + suffix! >hash-set pick
over intersect null?
[ swapd union [ [ suffix! ] keep ] dip swap ] [ drop ] if
1 + ;
: mian-chowla ( n -- seq )
[ V{ 1 } HS{ 2 } [ clone ] bi@ 2 ] dip
'[ pick length _ < ] [ next ] while 2drop ;
100 mian-chowla
[ 30 head "First 30 terms of the Mian-Chowla sequence:" ]
[ 10 tail* "Terms 91-100 of the Mian-Chowla sequence:" ] bi
[ print [ pprint bl ] each nl nl ] 2bi@

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redim as uinteger mian(0 to 1)
redim as uinteger sums(0 to 2)
mian(0) = 1 : mian(1) = 2
sums(0) = 2 : sums(1) = 3 : sums(2) = 4
dim as uinteger n_mc = 2, n_sm = 3, curr = 3, tempsum
while n_mc < 101
for i as uinteger = 0 to n_mc - 1
tempsum = curr + mian(i)
for j as uinteger = 0 to n_sm - 1
if tempsum = sums(j) then goto loopend
next j
next i
redim preserve as uinteger mian(0 to n_mc)
mian(n_mc) = curr
redim preserve as uinteger sums(0 to n_sm + n_mc)
for j as uinteger = 0 to n_mc - 1
sums(n_sm + j) = mian(j) + mian(n_mc)
next j
n_mc += 1
n_sm += n_mc
sums(n_sm-1) = 2*curr
loopend:
curr += 1
wend
print "Mian-Chowla numbers 1 through 30: ",
for i as uinteger = 0 to 29
print mian(i),
next i
print
print "Mian-Chowla numbers 91 through 100: ",
for i as uinteger = 90 to 99
print mian(i),
next i
print

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package main
import "fmt"
func contains(is []int, s int) bool {
for _, i := range is {
if s == i {
return true
}
}
return false
}
func mianChowla(n int) []int {
mc := make([]int, n)
mc[0] = 1
is := []int{2}
var sum int
for i := 1; i < n; i++ {
le := len(is)
jloop:
for j := mc[i-1] + 1; ; j++ {
mc[i] = j
for k := 0; k <= i; k++ {
sum = mc[k] + j
if contains(is, sum) {
is = is[0:le]
continue jloop
}
is = append(is, sum)
}
break
}
}
return mc
}
func main() {
mc := mianChowla(100)
fmt.Println("The first 30 terms of the Mian-Chowla sequence are:")
fmt.Println(mc[0:30])
fmt.Println("\nTerms 91 to 100 of the Mian-Chowla sequence are:")
fmt.Println(mc[90:100])
}

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package main
import "fmt"
type set map[int]bool
func mianChowla(n int) []int {
mc := make([]int, n)
mc[0] = 1
is := make(set, n*(n+1)/2)
is[2] = true
var sum int
isx := make([]int, 0, n)
for i := 1; i < n; i++ {
isx = isx[:0]
jloop:
for j := mc[i-1] + 1; ; j++ {
mc[i] = j
for k := 0; k <= i; k++ {
sum = mc[k] + j
if is[sum] {
isx = isx[:0]
continue jloop
}
isx = append(isx, sum)
}
for _, x := range isx {
is[x] = true
}
break
}
}
return mc
}
func main() {
mc := mianChowla(100)
fmt.Println("The first 30 terms of the Mian-Chowla sequence are:")
fmt.Println(mc[0:30])
fmt.Println("\nTerms 91 to 100 of the Mian-Chowla sequence are:")
fmt.Println(mc[90:100])
}

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import Data.Set (Set, fromList, insert, member)
------------------- MIAN-CHOWLA SEQUENCE -----------------
mianChowlas :: Int -> [Int]
mianChowlas =
reverse . snd . (iterate nextMC (fromList [2], [1]) !!) . subtract 1
nextMC :: (Set Int, [Int]) -> (Set Int, [Int])
nextMC (sumSet, mcs@(n:_)) =
(foldr insert sumSet ((2 * m) : fmap (m +) mcs), m : mcs)
where
valid x = not $ any (flip member sumSet . (x +)) mcs
m = until valid succ n
--------------------------- TEST -------------------------
main :: IO ()
main =
(putStrLn . unlines)
[ "First 30 terms of the Mian-Chowla series:"
, show (mianChowlas 30)
, []
, "Terms 91 to 100 of the Mian-Chowla series:"
, show $ drop 90 (mianChowlas 100)
]

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NB. http://rosettacode.org/wiki/Mian-Chowla_sequence
NB. Dreadfully inefficient implementation recomputes all the sums to n-1
NB. and computes the full addition table rather than just a triangular region
NB. However, this implementation is sufficiently quick to meet the requirements.
NB. The vector head is the next speculative value
NB. Beheaded, the vector is Mian-Chowla sequence.
Until =: conjunction def 'u^:(0 = v)^:_'
unique =: -:&# ~. NB. tally of list matches that of set
next_mc =: [: (, {.) (>:@:{. , }.)Until(unique@:((<:/~@i.@# #&, +/~)@:(}. , {.)))
prime_q =: 1&p: NB. for fun look at prime generation suitability

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import java.util.Arrays;
public class MianChowlaSequence {
public static void main(String[] args) {
long start = System.currentTimeMillis();
System.out.println("First 30 terms of the MianChowla sequence.");
mianChowla(1, 30);
System.out.println("Terms 91 through 100 of the MianChowla sequence.");
mianChowla(91, 100);
long end = System.currentTimeMillis();
System.out.printf("Elapsed = %d ms%n", (end-start));
}
private static void mianChowla(int minIndex, int maxIndex) {
int [] sums = new int[1];
int [] chowla = new int[maxIndex+1];
sums[0] = 2;
chowla[0] = 0;
chowla[1] = 1;
if ( minIndex == 1 ) {
System.out.printf("%d ", 1);
}
int chowlaLength = 1;
for ( int n = 2 ; n <= maxIndex ; n++ ) {
// Sequence is strictly increasing.
int test = chowla[n - 1];
// Bookkeeping. Generate only new sums.
int[] sumsNew = Arrays.copyOf(sums, sums.length + n);
int sumNewLength = sums.length;
int savedsSumNewLength = sumNewLength;
// Generate test candidates for the next value of the sequence.
boolean found = false;
while ( ! found ) {
test++;
found = true;
sumNewLength = savedsSumNewLength;
// Generate test sums
for ( int j = 0 ; j <= chowlaLength ; j++ ) {
int testSum = (j == 0 ? test : chowla[j]) + test;
boolean duplicate = false;
// Check if test Sum in array
for ( int k = 0 ; k < sumNewLength ; k++ ) {
if ( sumsNew[k] == testSum ) {
duplicate = true;
break;
}
}
if ( ! duplicate ) {
// Add to array
sumsNew[sumNewLength] = testSum;
sumNewLength++;
}
else {
// Duplicate found. Therefore, test candidate of the next value of the sequence is not OK.
found = false;
break;
}
}
}
// Bingo! Now update bookkeeping.
chowla[n] = test;
chowlaLength++;
sums = sumsNew;
if ( n >= minIndex ) {
System.out.printf("%d %s", chowla[n], (n==maxIndex ? "\n" : ""));
}
}
}
}

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(() => {
'use strict';
// main :: IO ()
const main = () => {
const genMianChowla = mianChowlas();
console.log([
'Mian-Chowla terms 1-30:',
take(30)(
genMianChowla
),
'\nMian-Chowla terms 91-100:',
(
drop(60)(genMianChowla),
take(10)(
genMianChowla
)
)
].join('\n') + '\n');
};
// mianChowlas :: Gen [Int]
function* mianChowlas() {
let
mcs = [1],
sumSet = new Set([2]),
x = 1;
while (true) {
yield x;
[sumSet, mcs, x] = nextMC(sumSet, mcs, x);
}
}
// nextMC :: Set Int -> [Int] -> Int -> (Set Int, [Int], Int)
const nextMC = (setSums, mcs, n) => {
// Set of sums -> Series up to n -> Next term in series
const valid = x => {
for (const m of mcs) {
if (setSums.has(x + m)) return false;
}
return true;
};
const x = until(valid)(x => 1 + x)(n);
return [
sumList(mcs)(x)
.reduce(
(a, n) => (a.add(n), a),
setSums
),
mcs.concat(x),
x
];
};
// sumList :: [Int] -> Int -> [Int]
const sumList = xs =>
// Series so far -> additional term -> new sums
n => [2 * n].concat(xs.map(x => n + x));
// ---------------- GENERIC FUNCTIONS ----------------
// drop :: Int -> [a] -> [a]
// drop :: Int -> Generator [a] -> Generator [a]
// drop :: Int -> String -> String
const drop = n =>
xs => Infinity > length(xs) ? (
xs.slice(n)
) : (take(n)(xs), xs);
// length :: [a] -> Int
const length = xs =>
// Returns Infinity over objects without finite
// length. This enables zip and zipWith to choose
// the shorter argument when one is non-finite,
// like cycle, repeat etc
'GeneratorFunction' !== xs.constructor
.constructor.name ? (
xs.length
) : Infinity;
// take :: Int -> [a] -> [a]
// take :: Int -> String -> String
const take = n =>
// The first n elements of a list,
// string of characters, or stream.
xs => 'GeneratorFunction' !== xs
.constructor.constructor.name ? (
xs.slice(0, n)
) : [].concat.apply([], Array.from({
length: n
}, () => {
const x = xs.next();
return x.done ? [] : [x.value];
}));
// until :: (a -> Bool) -> (a -> a) -> a -> a
const until = p =>
f => x => {
let v = x;
while (!p(v)) v = f(v);
return v;
};
// MAIN ---
return main();
})();

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@ -0,0 +1,23 @@
# Input: a bag-of-words (bow)
# Output: either an augmented bow, or nothing if a duplicate is found
def augment_while_unique(stream):
label $out
| foreach ((stream|tostring), null) as $word (.;
if $word == null then .
elif has($word) then break $out
else .[$word] = 1
end;
select($word == null) );
# For speedup, store "sums" as a hash
def mian_chowlas:
{m:[1], sums: {"1":1}}
| recurse(
.m as $m
| .sums as $sums
| first(range(1+$m[-1]; infinite) as $i
| $sums
| augment_while_unique( ($m[] | (.+$i)), (2*$i))
| [$i, .] ) as [$i, $sums]
| {m: ($m + [$i]), $sums} )
| .m[-1] ;

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@ -0,0 +1,3 @@
[limit(100; mian_chowlas)]
| "First thirty: \(.[:30]);",
"91st through 100th: \(.[90:])."

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function mianchowla(n)
seq = ones(Int, n)
sums = Dict{Int,Int}()
tempsums = Dict{Int,Int}()
for i in 2:n
seq[i] = seq[i - 1] + 1
incrementing = true
while incrementing
for j in 1:i
tsum = seq[j] + seq[i]
if haskey(sums, tsum)
seq[i] += 1
empty!(tempsums)
break
else
tempsums[tsum] = 0
if j == i
merge!(sums, tempsums)
empty!(tempsums)
incrementing = false
end
end
end
end
end
seq
end
function testmianchowla()
println("The first 30 terms of the Mian-Chowla sequence are $(mianchowla(30)).")
println("The 91st through 100th terms of the Mian-Chowla sequence are $(mianchowla(100)[91:100]).")
end
testmianchowla()
@time testmianchowla()

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@ -0,0 +1,36 @@
// Version 1.3.21
fun mianChowla(n: Int): List<Int> {
val mc = MutableList(n) { 0 }
mc[0] = 1
val hs = HashSet<Int>(n * (n + 1) / 2)
hs.add(2)
val hsx = mutableListOf<Int>()
for (i in 1 until n) {
hsx.clear()
var j = mc[i - 1]
outer@ while (true) {
j++
mc[i] = j
for (k in 0..i) {
val sum = mc[k] + j
if (hs.contains(sum)) {
hsx.clear()
continue@outer
}
hsx.add(sum)
}
hs.addAll(hsx)
break
}
}
return mc
}
fun main() {
val mc = mianChowla(100)
println("The first 30 terms of the Mian-Chowla sequence are:")
println(mc.subList(0, 30))
println("\nTerms 91 to 100 of the Mian-Chowla sequence are:")
println(mc.subList(90, 100))
}

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fun sumsRemainDistinct(candidate: Int, seq: Iterable<Int>, sums: MutableSet<Int>): Boolean {
val candidateSums = mutableListOf<Int>()
for (s in seq) {
when ((candidate + s) !in sums) {
true -> candidateSums.add(candidate + s)
false -> return false
}
}
with(sums) {
addAll(candidateSums)
add(candidate + candidate)
}
return true
}
fun mianChowla(n: Int): List<Int> {
val bufferSeq = linkedSetOf<Int>()
val bufferSums = linkedSetOf<Int>()
val sequence = generateSequence(1) { it + 1 } // [1,2,3,..]
.filter { sumsRemainDistinct(it, bufferSeq, bufferSums) }
.onEach { bufferSeq.add(it) }
return sequence.take(n).toList()
}
fun main() {
mianChowla(100).also {
println("Mian-Chowla[1..30] = ${it.take(30)}")
println("Mian-Chowla[91..100] = ${it.drop(90)}")
}
}

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@ -0,0 +1,15 @@
n = {m} = {1};
tmp = {2};
Do[
m++;
While[ContainsAny[tmp, m + n],
m++
];
tmp = Join[tmp, n + m];
AppendTo[tmp, 2 m];
AppendTo[n, m]
,
{99}
]
Row[Take[n, 30], ","]
Row[Take[n, {91, 100}], ","]

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@ -0,0 +1,35 @@
import intsets, strutils, times
proc mianchowla(n: Positive): seq[int] =
result = @[1]
var sums = [2].toIntSet()
var candidate = 1
while result.len < n:
# Test successive candidates.
var fit = false
result.add 0 # Make room for next value.
while not fit:
inc candidate
fit = true
result[^1] = candidate
# Check the sums.
for val in result:
if val + candidate in sums:
# Failed to satisfy criterium.
fit = false
break
# Add the new sums to the set of sums.
for val in result:
sums.incl val + candidate
let t0 = now()
let seq100 = mianchowla(100)
echo "The first 30 terms of the Mian-Chowla sequence are:"
echo seq100[0..29].join(" ")
echo ""
echo "Terms 91 to 100 of the sequence are:"
echo seq100[90..99].join(" ")
echo ""
echo "Computation time: ", (now() - t0).inMilliseconds, " ms"

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@ -0,0 +1,154 @@
program MianChowla;
//compiling with /usr/lib/fpc/3.2.0/ppcx64.2 -MDelphi -O4 -al "%f"
{$CODEALIGN proc=8,loop=4 }
uses
sysutils;
const
deltaK = 100;
maxCnt = 1000;
type
tElem = Uint32;
tpElem = pUint32;
t_n = array[0..maxCnt+1] of tElem;
t_n_sum_all = array[0..(maxCnt+1)*(maxCnt+2) DIV 2] of tElem;
var
n_LastPos,
n : t_n;
n_sum_all : t_n_sum_all;
maxIdx,
maxN,
max_SumIdx : NativeUInt;
procedure Init;
var
i : NativeInt;
begin
maxIdx := 1;
maxN := 1;
n[maxIdx] := maxN;
max_SumIdx := 1;
n_sum_all[max_SumIdx] := 2*maxN;
For i := 0 to maxCnt do
n_LastPos[i] := 1;
end;
procedure InsertNew_sum(NewValue:NativeUint);
//insertion already knowning the positions
var
pElem :tpElem;
InsIdx,chkIdx,oldIdx,newIdx : nativeInt;
Begin
newIdx := maxIdx;
oldIdx := max_SumIdx;
//append new value
inc(maxIdx);
n[maxIdx] := NewValue;
//extend sum_
inc(max_SumIdx,maxIdx);
//heighest value already known
InsIdx := max_SumIdx;
n_sum_all[InsIdx] := 2*NewValue;
//stop mark
n_sum_all[InsIdx+1] := High(tElem);
pElem := @n_sum_all[0];
dec(InsIdx);
//n_LastPos[newIdx]+newIdx-1 == InsIdx
repeat
//move old bigger values
chkIdx := n_LastPos[newIdx]+newIdx-1;
while InsIdx > chkIdx do
Begin
pElem[InsIdx] := pElem[oldIdx];
dec(InsIdx);
dec(oldIdx);
end;
//insert new value
pElem[InsIdx] := NewValue+n[newIdx];
dec(InsIdx);
dec(newIdx);
//all inserted
until newIdx <= 0;
//new minimum search position one behind, oldidx is one to small
inc(oldidx,2);
For newIdx := 1 to maxIdx do
n_LastPos[newIdx] := oldIdx;
end;
procedure FindNew;
var
pSumAll,pn : tpElem;
i,LastCheckPos,newValue,newSum : NativeUint;
TestRes : boolean;
begin
//start value = last inserted value
newValue := n[maxIdx];
pSumAll := @n_sum_all[0];
pn := @n[0];
repeat
//try next number
inc(newValue);
LastCheckPos := n_LastPos[1];
i := 1;
//check if sum = new is already n all_sum
repeat
newSum := newValue+pn[i];
IF LastCheckPos < n_LastPos[i] then
LastCheckPos := n_LastPos[i];
while pSumAll[LastCheckPos] < newSum do
inc(LastCheckPos);
//memorize LastCheckPos;
n_LastPos[i] := LastCheckPos;
TestRes:= pSumAll[LastCheckPos] = newSum;
IF TestRes then
BREAK;
inc(i);
until i>maxIdx;
//found?
If not(TestRes) then
BREAK;
until false;
InsertNew_sum(newValue);
end;
var
T1,T0: Int64;
i,k : NativeInt;
procedure Out_num(k:NativeInt);
Begin
T1 := GetTickCount64;
// k n[k] average dist last deltak total time
writeln(k:6,n[k]:12,(n[k]-n[k-deltaK+1]) DIV deltaK:8,T1-T0:8,' ms');
end;
BEGIN
writeln('Allocated memory ',2*SizeOf(t_n)+Sizeof(t_n_sum_all));
T0 := GetTickCount64;
while t0 = GetTickCount64 do;
T0 := GetTickCount64;
Init;
k := deltaK;
i := 1;
repeat
repeat
FindNew;
inc(i);
until i=k;
Out_num(k);
k := k+deltaK;
until k>maxCnt;
writeln;
writeln(#13,'The first 30 terms of the Mian-Chowla sequence are');
For i := 1 to 30 do
write(n[i],' ');
writeln;
writeln;
writeln('The terms 91 - 100 of the Mian-Chowla sequence are');
For i := 91 to 100 do
write(n[i],' ');
writeln;
END.

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@ -0,0 +1,22 @@
use strict;
use warnings;
use feature 'say';
sub generate_mc {
my($max) = @_;
my $index = 0;
my $test = 1;
my %sums = (2 => 1);
my @mc = 1;
while ($test++) {
my %these = %sums;
map { next if ++$these{$_ + $test} > 1 } @mc[0..$index], $test;
%sums = %these;
$index++;
return @mc if (push @mc, $test) > $max-1;
}
}
my @mian_chowla = generate_mc(100);
say "First 30 terms in the MianChowla sequence:\n", join(' ', @mian_chowla[ 0..29]),
"\nTerms 91 through 100:\n", join(' ', @mian_chowla[90..99]);

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@ -0,0 +1,42 @@
(phixonline)-->
<span style="color: #008080;">function</span> <span style="color: #000000;">mian_chowla</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;">sequence</span> <span style="color: #000000;">mc</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">1</span><span style="color: #0000FF;">},</span>
<span style="color: #000000;">is</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{</span><span style="color: #004600;">false</span><span style="color: #0000FF;">,</span><span style="color: #004600;">true</span><span style="color: #0000FF;">}</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">len_is</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">2</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">s</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">2</span> <span style="color: #008080;">to</span> <span style="color: #000000;">n</span> <span style="color: #008080;">do</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">isx</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{}</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">j</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">mc</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: #000000;">1</span>
<span style="color: #000000;">mc</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">append</span><span style="color: #0000FF;">(</span><span style="color: #000000;">mc</span><span style="color: #0000FF;">,</span><span style="color: #000000;">j</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">while</span> <span style="color: #004600;">true</span> <span style="color: #008080;">do</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: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">mc</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
<span style="color: #000000;">s</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">mc</span><span style="color: #0000FF;">[</span><span style="color: #000000;">k</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">+</span> <span style="color: #000000;">j</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">s</span><span style="color: #0000FF;"><=</span><span style="color: #000000;">len_is</span> <span style="color: #008080;">and</span> <span style="color: #000000;">is</span><span style="color: #0000FF;">[</span><span style="color: #000000;">s</span><span style="color: #0000FF;">]</span> <span style="color: #008080;">then</span>
<span style="color: #000000;">isx</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{}</span>
<span style="color: #008080;">exit</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #000000;">isx</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">append</span><span style="color: #0000FF;">(</span><span style="color: #000000;">isx</span><span style="color: #0000FF;">,</span><span style="color: #000000;">s</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">if</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">isx</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">then</span>
<span style="color: #000000;">s</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">isx</span><span style="color: #0000FF;">[$]</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">></span><span style="color: #000000;">len_is</span> <span style="color: #008080;">then</span>
<span style="color: #000000;">is</span> <span style="color: #0000FF;">&=</span> <span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #004600;">false</span><span style="color: #0000FF;">,</span><span style="color: #000000;">s</span><span style="color: #0000FF;">-</span><span style="color: #000000;">len_is</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">len_is</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">is</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</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: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">isx</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
<span style="color: #000000;">is</span><span style="color: #0000FF;">[</span><span style="color: #000000;">isx</span><span style="color: #0000FF;">[</span><span style="color: #000000;">k</span><span style="color: #0000FF;">]]</span> <span style="color: #0000FF;">=</span> <span style="color: #004600;">true</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">exit</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #000000;">j</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">1</span>
<span style="color: #000000;">mc</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">j</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">return</span> <span style="color: #000000;">mc</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">function</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: #004080;">sequence</span> <span style="color: #000000;">mc</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">mian_chowla</span><span style="color: #0000FF;">(</span><span style="color: #000000;">100</span><span style="color: #0000FF;">)</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;">"The first 30 terms of the Mian-Chowla sequence are:\n %V\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">mc</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..</span><span style="color: #000000;">30</span><span style="color: #0000FF;">]})</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;">"Terms 91 to 100 of the Mian-Chowla sequence are:\n %V\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">mc</span><span style="color: #0000FF;">[</span><span style="color: #000000;">91</span><span style="color: #0000FF;">..</span><span style="color: #000000;">100</span><span style="color: #0000FF;">]})</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;">"completed in %s\n"</span><span style="color: #0000FF;">,{</span><span style="color: #7060A8;">elapsed</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 +1,30 @@
from itertools import count, islice, chain
import time
def mian_chowla():
mc = [1]
yield mc[-1]
psums = set([2])
newsums = set([])
for trial in count(2):
for n in chain(mc, [trial]):
sum = n + trial
if sum in psums:
newsums.clear()
break
newsums.add(sum)
else:
psums |= newsums
newsums.clear()
mc.append(trial)
yield trial
def pretty(p, t, s, f):
print(p, t, " ".join(str(n) for n in (islice(mian_chowla(), s, f))))
if __name__ == '__main__':
st = time.time()
ts = "of the Mian-Chowla sequence are:\n"
pretty("The first 30 terms", ts, 0, 30)
pretty("\nTerms 91 to 100", ts, 90, 100)
print("\nComputation time was", (time.time()-st) * 1000, "ms")

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'''Mian-Chowla series'''
from itertools import (islice)
from time import time
# mianChowlas :: Gen [Int]
def mianChowlas():
'''Mian-Chowla series - Generator constructor
'''
mcs = [1]
sumSet = set([2])
x = 1
while True:
yield x
(sumSet, mcs, x) = nextMC(sumSet, mcs, x)
# nextMC :: (Set Int, [Int], Int) -> (Set Int, [Int], Int)
def nextMC(setSums, mcs, n):
'''(Set of sums, series so far, current term) ->
(updated sum set, updated series, next term)
'''
def valid(x):
for m in mcs:
if x + m in setSums:
return False
return True
x = until(valid)(succ)(n)
setSums.update(
[x + y for y in mcs] + [2 * x]
)
return (setSums, mcs + [x], x)
# TEST ----------------------------------------------------
# main :: IO ()
def main():
'''Tests'''
start = time()
genMianChowlas = mianChowlas()
print(
'First 30 terms of the Mian-Chowla series:\n',
take(30)(genMianChowlas)
)
drop(60)(genMianChowlas)
print(
'\n\nTerms 91 to 100 of the Mian-Chowla series:\n',
take(10)(genMianChowlas),
'\n'
)
print(
'(Computation time c. ' + str(round(
1000 * (time() - start)
)) + ' ms)'
)
# GENERIC -------------------------------------------------
# drop :: Int -> [a] -> [a]
# drop :: Int -> String -> String
def drop(n):
'''The suffix of xs after the
first n elements, or [] if n > length xs'''
def go(xs):
if isinstance(xs, list):
return xs[n:]
else:
take(n)(xs)
return xs
return lambda xs: go(xs)
# succ :: Int -> Int
def succ(x):
'''The successor of a numeric value (1 +)'''
return 1 + x
# 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))
)
# until :: (a -> Bool) -> (a -> a) -> a -> a
def until(p):
'''The result of applying f until p holds.
The initial seed value is x.'''
def go(f, x):
v = x
while not p(v):
v = f(v)
return v
return lambda f: lambda x: go(f, x)
if __name__ == '__main__':
main()

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[ stack ] is makeable ( --> s )
[ temp put
1 bit makeable put
' [ 1 ] 1
[ true temp put
1+
over witheach
[ over + bit
makeable share & if
[ false temp replace
conclude ] ]
temp take if
[ dup dip join
over witheach
[ over + bit
makeable take
| makeable put ] ]
over size temp share = until ]
makeable release
temp release
drop ] is mian-chowla ( n --> [ )
100 mian-chowla
30 split swap echo cr
-10 split nip echo

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/*REXX program computes and displays any range of the Mian─Chowla integer sequence.*/
parse arg LO HI . /*obtain optional arguments from the CL*/
if LO=='' | LO=="," then LO= 1 /*Not specified? Then use the default.*/
if HI=='' | HI=="," then HI= 30 /* " " " " " " */
r.= 0 /*initialize the rejects stemmed array.*/
#= 0 /*count of numbers in sequence (so far)*/
$= /*the Mian─Chowla sequence (so far). */
do t=1 until #=HI; @.= r.0 /*process numbers until range is filled*/
do i=1 for t; if r.i then iterate /*I already rejected? Then ignore it.*/
do j=i for t-i+1; if r.j then iterate /*J " " " " " */
_= i + j /*calculate the sum of I and J. */
if @._ then do; r.t= 1; iterate t; end /*reject T from Mian─Chowla sequence.*/
@._= 1 /*mark _ as one of the sequence sums.*/
end /*j*/
end /*i*/
#= # + 1 /*bump the counter of terms in the list*/
if #>=LO then if #<=HI then $= $ t /*In the specified range? Add to list.*/
end /*t*/
/*stick a fork in it, we're all done. */
say 'The MianChowla sequence for terms ' LO "──►" HI ' (inclusive):'
say strip($) /*ignore the leading superfluous blank.*/

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my @mian-chowla = 1, |(2..Inf).map: -> $test {
state $index = 1;
state %sums = 2 => 1;
my $next;
my %these;
@mian-chowla[^$index].map: { ++$next and last if %sums{$_ + $test}:exists; ++%these{$_ + $test} };
next if $next;
++%sums{$test + $test};
%sums.push: %these;
++$index;
$test
};
put "First 30 terms in the MianChowla sequence:\n", @mian-chowla[^30];
put "\nTerms 91 through 100:\n", @mian-chowla[90..99];

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require 'set'
n, ts, mc, sums = 100, [], [1], Set.new
sums << 2
st = Time.now
for i in (1 .. (n-1))
for j in mc[i-1]+1 .. Float::INFINITY
mc[i] = j
for k in (0 .. i)
if (sums.include?(sum = mc[k]+j))
ts.clear
break
end
ts << sum
end
if (ts.length > 0)
sums = sums | ts
break
end
end
end
et = (Time.now - st) * 1000
s = " of the Mian-Chowla sequence are:\n"
puts "The first 30 terms#{s}#{mc.slice(0..29).join(' ')}\n\n"
puts "Terms 91 to 100#{s}#{mc.slice(90..99).join(' ')}\n\n"
puts "Computation time was #{et.round(1)}ms."

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mian_chowla = Enumerator.new do |yielder|
mc, sums = [1], {}
1.step do |n|
mc << n
if mc.none?{|k| sums[k+n] } then
mc.each{|k| sums[k+n] = true }
yielder << n
else
mc.pop # n didn't work, get rid of it.
end
end
end
res = mian_chowla.take(100).to_a
s = " of the Mian-Chowla sequence are:\n"
puts "The first 30 terms#{s}#{res[0,30].join(' ')}\n
Terms 91 to 100#{s}#{res[90,10].join(' ')}"

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var (n, sums, ts, mc) = (100, Set([2]), [], [1])
var st = Time.micro_sec
for i in (1 ..^ n) {
for j in (mc[i-1]+1 .. Inf) {
mc[i] = j
for k in (0 .. i) {
var sum = mc[k]+j
if (sums.exists(sum)) {
ts.clear
break
}
ts << sum
}
if (ts.len > 0) {
sums = (sums|Set(ts...))
break
}
}
}
var et = (Time.micro_sec - st)
var s = " of the Mian-Chowla sequence are:\n"
say "The first 30 terms#{s}#{mc.ft(0, 29).join(' ')}\n"
say "Terms 91 to 100#{s}#{mc.ft(90, 99).join(' ')}\n"
say "Computation time was #{et} seconds."

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public func mianChowla(n: Int) -> [Int] {
var mc = Array(repeating: 0, count: n)
var ls = [2: true]
var sum = 0
mc[0] = 1
for i in 1..<n {
var lsx = [Int]()
jLoop: for j in (mc[i-1]+1)... {
mc[i] = j
for k in 0...i {
sum = mc[k] + j
if ls[sum] ?? false {
lsx = []
continue jLoop
}
lsx.append(sum)
}
for n in lsx {
ls[n] = true
}
break
}
}
return mc
}
let seq = mianChowla(n: 100)
print("First 30 terms in sequence are: \(Array(seq.prefix(30)))")
print("Terms 91 to 100 are: \(Array(seq[90..<100]))")

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' Mian-Chowla sequence - VBScript - 15/03/2019
Const m = 100, mm=28000
ReDim r(mm), v(mm * 2)
Dim n, t, i, j, l, s1, s2, iterate_t
ReDim seq(m)
t0=Timer
s1 = "1": s2 = ""
seq(1) = 1: n = 1: t = 1
Do While n < m
t = t + 1
iterate_t = False
For i = 1 to t * 2
v(i) = 0
Next
i = 1
Do While i <= t And Not iterate_t
If r(i) = 0 Then
j = i
Do While j <= t And Not iterate_t
If r(j) = 0 Then
l = i + j
If v(l) = 1 Then
r(t) = 1
iterate_t = True
End If
If Not iterate_t Then v(l) = 1
End If
j = j + 1
Loop
End If
i = i + 1
Loop
If Not iterate_t Then
n = n + 1
seq(n) = t
if n<= 30 then s1 = s1 & " " & t
if n>=91 and n<=100 then s2 = s2 & " " & t
End If
Loop
wscript.echo "t="& t
wscript.echo "The Mian-Chowla sequence for elements 1 to 30:"
wscript.echo s1
wscript.echo "The Mian-Chowla sequence for elements 91 to 100:"
wscript.echo s2
wscript.echo "Computation time: "& Int(Timer-t0) &" sec"

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' Mian-Chowla sequence - VBScript - March 19th, 2019
Function Find(x(), val) ' finds val on a pre-sorted list
Dim l, u, h : l = 0 : u = ubound(x) : Do : h = (l + u) \ 2
If val = x(h) Then Find = h : Exit Function
If val > x(h) Then l = h + 1 Else u = h - 1
Loop Until l > u : Find = -1
End Function
' adds next item from a() to result (r()), adds all remaining items
' from b(), once a() is exhausted
Sub Shuffle(ByRef r(), a(), b(), ByRef i, ByRef ai, ByRef bi, al, bl)
r(i) = a(ai) : ai = ai + 1 : If ai > al Then Do : i = i + 1 : _
r(i) = b(bi) : bi = bi + 1 : Loop until bi = bl
End Sub
Function Merger(a(), b(), bl) ' merges two pre-sorted lists
Dim res(), ai, bi, i : ReDim res(ubound(a) + bl) : ai = 0 : bi = 0
For i = 0 To ubound(res)
If a(ai) < b(bi) Then Shuffle res, a, b, i, ai, bi, ubound(a), bl _
Else Shuffle res, b, a, i, bi, ai, bl, ubound(a)
Next : Merger = res
End Function
Const n = 100 : Dim mc(), sums(), ts(), sp, tc : sp = 1 : tc = 0
ReDim mc(n - 1), sums(0), ts(n - 1) : mc(0) = 1 : sums(sp - 1) = 2
Dim sum, i, j, k, st : st = Timer
wscript.echo "The Mian-Chowla sequence for elements 1 to 30:"
wscript.stdout.write("1 ")
For i = 1 To n - 1 : j = mc(i - 1) + 1 : Do
mc(i) = j : For k = 0 To i
sum = mc(k) + j : If Find(sums, sum) >= 0 Then _
tc = 0 : Exit For Else ts(tc) = sum : tc = tc + 1
Next : If tc > 0 Then
nu = Merger(sums, ts, tc) : ReDim sums(ubound(nu))
For e = 0 To ubound(nu) : sums(e) = nu(e) : Next
tc = 0 : Exit Do
End If : j = j + 1 : Loop
if i = 90 then wscript.echo vblf & vbLf & _
"The Mian-Chowla sequence for elements 91 to 100:"
If i < 30 or i >= 90 Then wscript.stdout.write(mc(i) & " ")
Next
wscript.echo vblf & vbLf & "Computation time: "& Timer - st &" seconds."

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Module Module1
Function MianChowla(ByVal n As Integer) As Integer()
Dim mc(n - 1) As Integer, sums, ts As New HashSet(Of Integer),
sum As Integer : mc(0) = 1 : sums.Add(2)
For i As Integer = 1 To n - 1
For j As Integer = mc(i - 1) + 1 To Integer.MaxValue
mc(i) = j
For k As Integer = 0 To i
sum = mc(k) + j
If sums.Contains(sum) Then ts.Clear() : Exit For
ts.Add(sum)
Next
If ts.Count > 0 Then sums.UnionWith(ts) : Exit For
Next
Next
Return mc
End Function
Sub Main(ByVal args As String())
Const n As Integer = 100
Dim sw As New Stopwatch(), str As String = " of the Mian-Chowla sequence are:" & vbLf
sw.Start() : Dim mc As Integer() = MianChowla(n) : sw.Stop()
Console.Write("The first 30 terms{1}{2}{0}{0}Terms 91 to 100{1}{3}{0}{0}" &
"Computation time was {4}ms.{0}", vbLf, str,
String.Join(" ", mc.Take(30)), String.Join(" ", mc.Skip(n - 10)), sw.ElapsedMilliseconds)
End Sub
End Module

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var mianChowla = Fn.new { |n|
var mc = List.filled(n, 0)
var sums = {}
var ts = {}
mc[0] = 1
sums[2] = true
for (i in 1...n) {
var j = mc[i-1] + 1
while (true) {
mc[i] = j
for (k in 0..i) {
var sum = mc[k] + j
if (sums[sum]) {
ts.clear()
break
}
ts[sum] = true
}
if (ts.count > 0) {
for (key in ts.keys) sums[key] = true
break
}
j = j + 1
}
}
return mc
}
var start = System.clock
var mc = mianChowla.call(100)
System.print("The first 30 terms of the Mian-Chowla sequence are:\n%(mc[0..29].join(" "))")
System.print("\nTerms 91 to 100 of the Mian-Chowla sequence are:\n%(mc[90..99].join(" "))")
System.print("\nTook %(((System.clock - start)*1000).round) milliseconds")

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@ -0,0 +1,49 @@
define N = 100;
define NN = (N * (N+1)) >> 1;
func Contains(Lst, Item, Size);
int Lst, Item, Size, I;
[for I:= Size-1 downto 0 do
if Item = Lst(I) then return true;
return false;
];
int MC(N);
proc MianChowla;
int Sums(NN), Sum, LE, SS, I, J, K;
[MC(0):= 1;
Sums(0):= 2;
SS:= 1;
for I:= 1 to N-1 do
[LE:= SS;
J:= MC(I-1) + 1;
MC(I):= J;
K:= 0;
loop [Sum:= MC(K) + J;
if Contains(Sums, Sum, SS) then
[SS:= LE;
J:= J+1;
MC(I):= J;
K:= 0;
]
else
[Sums(SS):= Sum;
SS:= SS+1;
K:= K+1;
if K > I then quit;
];
];
];
];
int I;
[MianChowla;
Text(0, "The first 30 terms of the Mian-Chowla sequence are:^m^j");
for I:= 0 to 30-1 do
[IntOut(0, MC(I)); ChOut(0, ^ )];
Text(0, "^m^j^m^jTerms 91 to 100 of the Mian-Chowla sequence are:^m^j");
for I:= 90 to 100-1 do
[IntOut(0, MC(I)); ChOut(0, ^ )];
CrLf(0);
]