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Ingy döt Net 2023-07-01 11:58:00 -04:00
parent 7387c8f97b
commit cb5bb5e222
199093 changed files with 3378972 additions and 0 deletions

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---
from: http://rosettacode.org/wiki/Ormiston_triples

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;Definition
An '''Ormiston triple''' is three consecutive prime numbers which are anagrams, i.e. contain the same decimal digits but in a different order.
;Example
The three consecutive primes '''(11117123, 11117213, 11117321)''' are an Ormiston triple.
;Task
* Find and show the smallest member of the first '''25''' Ormiston triples.
* Find and show the '''count''' of Ormiston triples up to one billion.
;Stretch
* Find and show the '''count''' of Ormiston triples up to ten billion.
;Reference
* [[oeis:A075093 |OEIS:A075093 - Smallest member of Ormiston prime triple]]
;Related task
* [[Ormiston pairs]]
<br>

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#include <array>
#include <iostream>
#include <primesieve.hpp>
class ormiston_triple_generator {
public:
ormiston_triple_generator() {
for (int i = 0; i < 2; ++i) {
primes_[i] = pi_.next_prime();
digits_[i] = get_digits(primes_[i]);
}
}
std::array<uint64_t, 3> next_triple() {
for (;;) {
uint64_t prime = pi_.next_prime();
auto digits = get_digits(prime);
bool is_triple = digits == digits_[0] && digits == digits_[1];
uint64_t prime0 = primes_[0];
primes_[0] = primes_[1];
primes_[1] = prime;
digits_[0] = digits_[1];
digits_[1] = digits;
if (is_triple)
return {prime0, primes_[0], primes_[1]};
}
}
private:
static std::array<int, 10> get_digits(uint64_t n) {
std::array<int, 10> result = {};
for (; n > 0; n /= 10)
++result[n % 10];
return result;
}
primesieve::iterator pi_;
std::array<uint64_t, 2> primes_;
std::array<std::array<int, 10>, 2> digits_;
};
int main() {
ormiston_triple_generator generator;
int count = 0;
std::cout << "Smallest members of first 25 Ormiston triples:\n";
for (; count < 25; ++count) {
auto primes = generator.next_triple();
std::cout << primes[0] << ((count + 1) % 5 == 0 ? '\n' : ' ');
}
std::cout << '\n';
for (uint64_t limit = 1000000000; limit <= 10000000000; ++count) {
auto primes = generator.next_triple();
if (primes[2] > limit) {
std::cout << "Number of Ormiston triples < " << limit << ": "
<< count << '\n';
limit *= 10;
}
}
}

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#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <stdint.h>
#include <locale.h>
bool *sieve(uint64_t limit) {
uint64_t i, p;
limit++;
// True denotes composite, false denotes prime.
bool *c = calloc(limit, sizeof(bool)); // all false by default
c[0] = true;
c[1] = true;
for (i = 4; i < limit; i += 2) c[i] = true;
p = 3; // Start from 3.
while (true) {
uint64_t p2 = p * p;
if (p2 >= limit) break;
for (i = p2; i < limit; i += 2 * p) c[i] = true;
while (true) {
p += 2;
if (!c[p]) break;
}
}
return c;
}
typedef struct {
char digs[20];
int count;
} digits;
digits getDigits(uint64_t n) {
if (n == 0) return (digits){ {0}, 1 };
digits d;
d.count = 0;
while (n > 0) {
d.digs[d.count++] = n % 10;
n = n / 10;
}
return d; // note digits are in reverse order
}
int main() {
const uint64_t limit = 10000000000;
uint64_t i, j, pc = 0, p1, p2, p3, key1, key2, key3;
int k, count, count2;
digits d;
bool *c = sieve(limit);
for (i = 0; i < limit; ++i) {
if (!c[i]) ++pc;
}
uint64_t *primes = (uint64_t *)malloc(pc * sizeof(uint64_t));
for (i = 0, j = 0; i < limit; ++i) {
if (!c[i]) primes[j++] = i;
}
free(c);
uint64_t orm25[25];
int counts[2];
j = limit/10;
for (i = 0; i < pc-2; ++i) {
p1 = primes[i];
p2 = primes[i+1];
p3 = primes[i+2];
if ((p2 - p1) % 18 || (p3 - p2) % 18) continue;
key1 = 1;
d = getDigits(p1);
for (k = 0; k < d.count; ++k) key1 *= primes[d.digs[k]];
key2 = 1;
d = getDigits(p2);
for (k = 0; k < d.count; ++k) key2 *= primes[d.digs[k]];
if (key1 != key2) continue;
key3 = 1;
d = getDigits(p3);
for (k = 0; k < d.count; ++k) key3 *= primes[d.digs[k]];
if (key2 == key3) {
if (count < 25) orm25[count] = p1;
if (p1 >= j) {
counts[count2++] = count;
j *= 10;
}
++count;
}
}
counts[count2] = count;
printf("Smallest members of first 25 Ormiston triples:\n");
setlocale(LC_NUMERIC, "");
for (i = 0; i < 25; ++i) {
printf("%'10ld ", orm25[i]);
if (!((i+1) % 5)) printf("\n");
}
printf("\n");
j = limit/10;
for (i = 0; i < 2; ++i) {
printf("%'d Ormiston triples before %'ld\n", counts[i], j);
j *= 10;
printf("\n");
}
free(primes);
return 0;
}

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{Bit boolean - because it stores 8 bools per bytye, it will}
{handle up to 16 gigabyte in a 32 bit programming environment}
type TBitBoolArray = class(TObject)
private
FSize: int64;
ByteArray: array of Byte;
function GetValue(Index: int64): boolean;
procedure WriteValue(Index: int64; const Value: boolean);
function GetSize: int64;
procedure SetSize(const Value: int64);
protected
public
property Value[Index: int64]: boolean read GetValue write WriteValue; default;
constructor Create;
property Count: int64 read GetSize write SetSize;
procedure Clear(Value: boolean);
end;
{ TBitBoolArray }
const BitArray: array [0..7] of byte = ($01, $02, $04, $08, $10, $20, $40, $80);
function TBitBoolArray.GetValue(Index: int64): boolean;
begin
{Note: (Index and 7) is faster than (Index mod 8)}
Result:=(ByteArray[Index shr 3] and BitArray[Index and 7])<>0;
end;
procedure TBitBoolArray.WriteValue(Index: int64; const Value: boolean);
var Inx: int64;
begin
Inx:=Index shr 3;
{Note: (Index and 7) is faster than (Index mod 8)}
if Value then ByteArray[Inx]:=ByteArray[Inx] or BitArray[Index and 7]
else ByteArray[Inx]:=ByteArray[Inx] and not BitArray[Index and 7]
end;
constructor TBitBoolArray.Create;
begin
SetLength(ByteArray,0);
end;
function TBitBoolArray.GetSize: int64;
begin
Result:=FSize;
end;
procedure TBitBoolArray.SetSize(const Value: int64);
var Len: int64;
begin
FSize:=Value;
{Storing 8 items per byte}
Len:=Value div 8;
{We need one more to fill partial bits}
if (Value mod 8)<>0 then Inc(Len);
SetLength(ByteArray,Len);
end;
procedure TBitBoolArray.Clear(Value: boolean);
var Fill: byte;
begin
if Value then Fill:=$FF else Fill:=0;
FillChar(ByteArray[0],Length(ByteArray),Fill);
end;
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++
{Sieve object the generates and holds prime values}
{Enable this flag if you need primes past 2 billion.
The flag signals the code to use bit-booleans arrays
which can contain up to 8 x 4 gigabytes = 32 gig booleans.}
{$define BITBOOL}
type TPrimeSieve = class(TObject)
private
{$ifdef BITBOOL}
PrimeArray: TBitBoolArray;
{$else}
PrimeArray: array of boolean;
{$endif}
FArraySize: int64;
function GetPrime(Index: int64): boolean;
procedure Clear;
protected
procedure DoSieve;
property ArraySize: int64 read FArraySize;
public
BitBoolean: boolean;
constructor Create;
destructor Destroy; override;
procedure Intialize(Size: int64);
property Prime[Index: int64]: boolean read GetPrime; default;
function NextPrime(Start: int64): int64;
end;
procedure TPrimeSieve.Clear;
begin
{$ifdef BITBOOL}
PrimeArray.Clear(True);
{$else}
FillChar(PrimeArray[0],Length(PrimeArray),True);
{$endif}
end;
constructor TPrimeSieve.Create;
begin
{$ifdef BITBOOL}
PrimeArray:=TBitBoolArray.Create;
BitBoolean:=True;
{$else}
BitBoolean:=False;
{$endif}
end;
destructor TPrimeSieve.Destroy;
begin
{$ifdef BITBOOL}
PrimeArray.Free;
{$endif}
inherited;
end;
procedure TPrimeSieve.DoSieve;
{Load flags with true/false to flag that number is prime}
{Note: does not store even values, because except for 2, all primes are even}
{Starts storing flags at Index=3, so reading/writing routines compensate}
{Uses for-loops for boolean arrays and while-loops for bitbooleans arrays}
{$ifdef BITBOOL}
var Offset, I, K: int64;
{$else}
var Offset, I, K: cardinal;
{$endif}
begin
Clear;
{$ifdef BITBOOL}
I:=0;
while I<ArraySize do
{$else}
for I:=0 to ArraySize-1 do
{$endif}
begin
if PrimeArray[I] then
begin
Offset:= I + I + 3;
K:= I + Offset;
while K <=(ArraySize-1) do
begin
PrimeArray[K]:= False;
K:= K + Offset;
end;
end;
{$ifdef BITBOOL} Inc(I); {$endif}
end;
end;
function TPrimeSieve.GetPrime(Index: int64): boolean;
{Get a prime flag from array - compensates}
{ for 0,1,2 and even numbers not being stored}
begin
if Index in [0,1,2] then Result:=True
else if (Index and 1)=0 then Result:=false
else Result:=PrimeArray[(Index div 2)-1];
end;
function TPrimeSieve.NextPrime(Start: int64): int64;
{Get next prime after Start}
begin
Result:=Start+1;
while Result<=((ArraySize-1) * 2) do
begin
if Self.Prime[Result] then break;
Inc(Result);
end;
end;
procedure TPrimeSieve.Intialize(Size: int64);
{Set array size and do Sieve to load flag array with}
begin
FArraySize:=Size div 2;
{$ifdef BITBOOL}
PrimeArray.Count:=FArraySize;
{$else}
SetLength(PrimeArray,FArraySize);
{$endif}
DoSieve;
end;
{-------------------------------------------------------------------------------}
type TTripleInfo = record
Prime1,Prime2,Prime3: int64;
Count: int64;
end;
{Iterator for Ormiston Triple}
type TOrm3Iterator = class(TObject)
FInfo: TTripleInfo;
PS: TPrimeSieve;
private
function IsOrmistonTriple(P1, P2, P3: int64): boolean;
function EncodeNumber(N: int64): int64;
protected
public
procedure Reset;
procedure SetSize(Size: int64);
function GetNext(Limit: int64; var Info: TTripleInfo): boolean;
constructor Create;
destructor Destroy; override;
end;
procedure TOrm3Iterator.Reset;
{Restart iterator}
begin
FInfo.Count:=0;
FInfo.Prime1:=1; FInfo.Prime2:=3; FInfo.Prime3:=5;
end;
procedure TOrm3Iterator.SetSize(Size: int64);
begin
PS.Intialize(Size);
Reset;
end;
constructor TOrm3Iterator.Create;
begin
PS:=TPrimeSieve.Create;
{Start with trivial prime set}
SetSize(100);
end;
destructor TOrm3Iterator.Destroy;
begin
PS.Free;
inherited;
end;
function TOrm3Iterator.EncodeNumber(N: int64): int64;
{Encode N by counting digits 0..9 into nibbles}
{Get the product of the integers in a number}
var T: integer;
const NibMap: array [0..9] of int64 = (
{0} $1, {1} $10, {2} $100, {3} $1000, {4} $10000, {5} $100000,
{6} $1000000, {7} $10000000, {8} $100000000, {9} $1000000000);
begin
Result:=0;
repeat
begin
T:=N mod 10;
N:=N div 10;
Result:=Result + NibMap[T];
end
until N<1;
end;
function TOrm3Iterator.IsOrmistonTriple(P1,P2,P3: int64): boolean;
var Pd1,Pd2,Pd3: int64;
begin
Result:=False;
{Optimization - difference in primes should be multiple of 18}
if (((P2 - P1) mod 18)<>0) or (((p3 - p2) mod 18)<>0) then exit;
Pd1:=EncodeNumber(P1);
Pd2:=EncodeNumber(P2);
if Pd1<>Pd2 then exit;
Pd3:=EncodeNumber(P3);
Result:=Pd2=Pd3;
end;
function TOrm3Iterator.GetNext(Limit: int64; var Info: TTripleInfo): boolean;
{Iterate to next Ormiston Pair - automatically stop at prime>Limit}
{Returns false if it hits limit - true if it found Next Ormiston Pair}
begin
Result:=False;
while true do
begin
{Get next set of primes}
FInfo.Prime1:=FInfo.Prime2;
FInfo.Prime2:=FInfo.Prime3;
FInfo.Prime3:=PS.NextPrime(FInfo.Prime3);
{Abort if 3rd prime is ove limit}
if FInfo.Prime3>=Limit then break;
{Test if it is an Ormiston triple}
if IsOrmistonTriple(FInfo.Prime1,FInfo.Prime2,FInfo.Prime3) then
begin
{Return info on triple}
Inc(FInfo.Count);
Info:=FInfo;
Result:=True;
break;
end;
end;
end;
procedure ShowOrmistonTriple(Memo: TMemo);
var I: integer;
var S: string;
var OI: TOrm3Iterator;
var Info: TTripleInfo;
const Limit = 10000000000;
const DisMod = Limit div 10000000;
const Bill = Limit div 1000000000;
var NS: string;
procedure DisplayTitle;
begin
NS:=IntToStr(Bill)+'-Billion';
Memo.Lines.Add('====== Find Ormiston Triples ======');
Memo.Lines.Add('First 25 plus number to '+NS);
S:='Bit-Boolean Array: ';
if OI.PS.BitBoolean then S:=S+'Yes' else S:=S+'No';
Memo.Lines.Add(S);
end;
begin
{Create iterator}
OI:=TOrm3Iterator.Create;
try
DisplayTitle;
Memo.Lines.Add('Sieving Primes');
OI.SetSize(Limit);
Memo.Lines.Add('Finding first 25 Triples');
{Iterate throug 1st 25 tuples}
for I:=1 to 25 do
begin
OI.GetNext(High(Int64),Info);
Memo.Lines.Add(Format('%3d - (%6D %6D %6D) ',[I,Info.Prime1,Info.Prime2,Info.Prime3]));
end;
Memo.Lines.Add('Count='+IntToStr(Info.Count));
Memo.Lines.Add('Counting triples to '+NS);
{Iterate to limit number of triples}
while OI.GetNext(Limit,Info) do
if (Info.Count mod DisMod)=0 then Memo.Lines.Add('Count='+IntToStr(Info.Count));
Memo.Lines.Add(NS+'='+IntToStr(Info.Count));
finally OI.Free; end;
end;

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// Ormiston triples. Nigel Galloway: February 3rd., 2023
let oTriples n=n|>Seq.pairwise|>Seq.filter(fun((n,i),(g,l))->i=g)|>Seq.map(fun((n,i),(g,l))->(n,g,l))
primes32()|>oPairs|>oTriples|>Seq.take 25|>Seq.iter(fun(n,_,_)->printf "%d " n); printfn ""
printfn $"<100 million: %d{primes32()|>Seq.takeWhile((>)100000000)|>oPairs|>oTriples|>Seq.length}"
printfn $"<1 billion: %d{primes32()|>Seq.takeWhile((>)1000000000)|>oPairs|>oTriples|>Seq.length}"

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program Ormiston;
{$IFDEF FPC}{$MODE DELPHI} {$OPTIMIZATION ON,ALL}{$ENDIF}
{$IFDEF WINDOWS}{$APPLICATION CONSOLE}{$ENDIF}
uses
sysutils,strUtils;
//********* segmented sieve of erathostenes *********
{segmented sieve of Erathostenes using only odd numbers}
{using presieved sieve of small primes, to reduce the most time consuming}
const
smlPrimes :array [0..10] of Byte = (2,3,5,7,11,13,17,19,23,29,31);
maxPreSievePrimeNum = 7;
maxPreSievePrime = 17;//smlPrimes[maxPreSievePrimeNum];
cSieveSize = 4*16384;//<= High(Word)+1 // Level I Data Cache
type
tSievePrim = record
svdeltaPrime:word;//diff between actual and new prime
svSivOfs:word; //Offset in sieve
svSivNum:LongWord;//1 shl (1+16+32) = 5.6e14
end;
tpSievePrim = ^tSievePrim;
var
//sieved with primes 3..maxPreSievePrime.here about 255255 Byte
{$ALIGN 32}
preSieve :array[0..3*5*7*11*13*17-1] of Byte;//must be > cSieveSize
{$ALIGN 32}
Sieve :array[0..cSieveSize-1] of Byte;
{$ALIGN 32}
//prime = FoundPrimesOffset + 2*FoundPrimes[0..FoundPrimesCnt]
FoundPrimes : array[0..12252] of Word;
{$ALIGN 32}
sievePrimes : array[0..1077863] of tSievePrim;
FoundPrimesOffset : Uint64;
FoundPrimesCnt,
FoundPrimesIdx,
FoundPrimesTotal,
SieveNum,
SieveMaxIdx,
preSieveOffset,
LastInsertedSievePrime :NativeUInt;
procedure CopyPreSieveInSieve; forward;
procedure CollectPrimes; forward;
procedure sieveOneSieve; forward;
procedure Init0Sieve; forward;
procedure SieveOneBlock; forward;
procedure preSieveInit;
var
i,pr,j,umf : NativeInt;
Begin
fillchar(preSieve[0],SizeOf(preSieve),#1);
i := 1;
pr := 3;// starts with pr = 3
umf := 1;
repeat
IF preSieve[i] =1 then
Begin
pr := 2*i+1;
j := i;
repeat
preSieve[j] := 0;
inc(j,pr);
until j> High(preSieve);
umf := umf*pr;
end;
inc(i);
until (pr = maxPreSievePrime)OR(umf>High(preSieve)) ;
preSieveOffset := 0;
end;
function InsertSievePrimes(PrimPos:NativeInt):NativeInt;
var
j :NativeUINt;
i,pr : NativeUInt;
begin
i := 0;
//ignore first primes already sieved with
if SieveNum = 0 then
i := maxPreSievePrimeNum;
pr :=0;
j := Uint64(SieveNum)*cSieveSize*2-LastInsertedSievePrime;
with sievePrimes[PrimPos] do
Begin
pr := FoundPrimes[i]*2+1;
svdeltaPrime := pr+j;
j := pr;
end;
inc(PrimPos);
for i := i+1 to FoundPrimesCnt-1 do
Begin
IF PrimPos > High(sievePrimes) then
BREAK;
with sievePrimes[PrimPos] do
Begin
pr := FoundPrimes[i]*2+1;
svdeltaPrime := (pr-j);
j := pr;
end;
inc(PrimPos);
end;
LastInsertedSievePrime :=Uint64(SieveNum)*cSieveSize*2+pr;
result := PrimPos;
end;
procedure CalcSievePrimOfs(lmt:NativeUint);
//lmt High(sievePrimes)
var
i,pr : NativeUInt;
sq : Uint64;
begin
pr := 0;
i := 0;
repeat
with sievePrimes[i] do
Begin
pr := pr+svdeltaPrime;
IF sqr(pr) < (cSieveSize*2) then
Begin
svSivNum := 0;
svSivOfs := (pr*pr-1) DIV 2;
end
else
Begin
SieveMaxIdx := i;
pr := pr-svdeltaPrime;
BREAK;
end;
end;
inc(i);
until i > lmt;
for i := i to lmt do
begin
with sievePrimes[i] do
Begin
pr := pr+svdeltaPrime;
sq := sqr(pr);
svSivNum := sq DIV (2*cSieveSize);
svSivOfs := ( (sq - Uint64(svSivNum)*(2*cSieveSize))-1)DIV 2;
end;
end;
end;
procedure sievePrimesInit;
var
i,j,pr,PrimPos:NativeInt;
Begin
LastInsertedSievePrime := 0;
preSieveOffset := 0;
SieveNum :=0;
CopyPreSieveInSieve;
//normal sieving of first sieve
i := 1; // start with 3
repeat
while Sieve[i] = 0 do
inc(i);
pr := 2*i+1;
inc(i);
j := ((pr*pr)-1) DIV 2;
if j > High(Sieve) then
BREAK;
repeat
Sieve[j] := 0;
inc(j,pr);
until j > High(Sieve);
until false;
CollectPrimes;
PrimPos := InsertSievePrimes(0);
LastInsertedSievePrime := FoundPrimes[PrimPos]*2+1;
IF PrimPos < High(sievePrimes) then
Begin
Init0Sieve;
sieveOneBlock;
repeat
sieveOneBlock;
dec(SieveNum);
PrimPos := InsertSievePrimes(PrimPos);
inc(SieveNum);
until PrimPos > High(sievePrimes);
end;
Init0Sieve;
end;
procedure Init0Sieve;
begin
FoundPrimesTotal :=0;
preSieveOffset := 0;
SieveNum :=0;
CalcSievePrimOfs(High(sievePrimes));
end;
procedure CopyPreSieveInSieve;
var
lmt : NativeInt;
Begin
lmt := preSieveOffset+cSieveSize;
lmt := lmt-(High(preSieve)+1);
IF lmt<= 0 then
begin
Move(preSieve[preSieveOffset],Sieve[0],cSieveSize);
if lmt <> 0 then
inc(preSieveOffset,cSieveSize)
else
preSieveOffset := 0;
end
else
begin
Move(preSieve[preSieveOffset],Sieve[0],cSieveSize-lmt);
Move(preSieve[0],Sieve[cSieveSize-lmt],lmt);
preSieveOffset := lmt
end;
end;
procedure sieveOneSieve;
var
sp:tpSievePrim;
pSieve :pByte;
i,j,pr,sn,dSievNum :NativeUint;
Begin
pr := 0;
sn := sieveNum;
sp := @sievePrimes[0];
pSieve := @Sieve[0];
For i := SieveMaxIdx downto 0 do
with sp^ do
begin
pr := pr+svdeltaPrime;
IF svSivNum = sn then
Begin
j := svSivOfs;
repeat
pSieve[j] := 0;
inc(j,pr);
until j > High(Sieve);
dSievNum := j DIV cSieveSize;
svSivOfs := j-dSievNum*cSieveSize;
svSivNum := sn+dSievNum;
end;
inc(sp);
end;
i := SieveMaxIdx+1;
repeat
if i > High(SievePrimes) then
BREAK;
with sp^ do
begin
if svSivNum > sn then
Begin
SieveMaxIdx := I-1;
Break;
end;
pr := pr+svdeltaPrime;
j := svSivOfs;
repeat
Sieve[j] := 0;
inc(j,pr);
until j > High(Sieve);
dSievNum := j DIV cSieveSize;
svSivOfs := j-dSievNum*cSieveSize;
svSivNum := sn+dSievNum;
end;
inc(i);
inc(sp);
until false;
end;
procedure CollectPrimes;
//extract primes to FoundPrimes
var
pSieve : pbyte;
pFound : pWord;
i,idx : NativeUint;
Begin
FoundPrimesOffset := SieveNum*2*cSieveSize;
FoundPrimesIdx := 0;
pFound :=@FoundPrimes[0];
i := 0;
idx := 0;
IF SieveNum = 0 then
//include small primes used to pre-sieve
Begin
repeat
pFound[idx]:= (smlPrimes[idx]-1) DIV 2;
inc(idx);
until smlPrimes[idx]>maxPreSievePrime;
i := (smlPrimes[idx] -1) DIV 2;
end;
//grabbing the primes without if then -> reduces time extremly
//primes are born to let branch-prediction fail.
pSieve:= @Sieve[Low(Sieve)];
repeat
//store every value until a prime aka 1 is found
pFound[idx]:= i;
inc(idx,pSieve[i]);
inc(i);
until i>High(Sieve);
FoundPrimesCnt:= idx;
inc(FoundPrimesTotal,Idx);
end;
procedure SieveOneBlock;
begin
CopyPreSieveInSieve;
sieveOneSieve;
CollectPrimes;
inc(SieveNum);
end;
function Nextprime:Uint64;
Begin
result := FoundPrimes[FoundPrimesIdx]*2+1+FoundPrimesOffset;
if (FoundPrimesIdx=0) AND (sievenum = 1) then
inc(result);
inc(FoundPrimesIdx);
If FoundPrimesIdx>= FoundPrimesCnt then
SieveOneBlock;
end;
function PosOfPrime: Uint64;inline;
Begin
result := FoundPrimesTotal-FoundPrimesCnt+FoundPrimesIdx;
end;
function TotalCount :Uint64;inline;
begin
result := FoundPrimesTotal;
end;
function SieveSize :LongInt;inline;
Begin
result := 2*cSieveSize;
end;
function SieveStart:Uint64;inline;
Begin
result := (SieveNum-1)*2*cSieveSize;
end;
procedure InitPrime;
Begin
Init0Sieve;
SieveOneBlock;
end;
//********* segmented sieve of erathostenes *********
const
Limit= 10*1000*1000*1000;
type
tDigits10 = array[0..15] of byte;
td10_UsedDgts2 = array[0..3] of Uint32;
td10_UsedDgts3 = array[0..1] of Uint64;
tpd10_UsedDgts3 = ^td10_UsedDgts3;
procedure OutIn(cnt,p1:NativeInt);
Begin
write(Numb2USA(IntToStr(p1)):13,' ');
if cnt MOD 5 = 0 then
writeln;
end;
function OutByPot10(cnt,prLimit:NativeInt):NativeInt;
Begin
writeln(Numb2USA(IntToStr(cnt)):12,' Ormiston triples before ',Numb2USA(IntToStr(prLimit)):14);
result := 10*prLimit;
end;
function Convert2Digits10(p:NativeUint):Uint64;inline;
const
smlPrimes : array[0..9] of integer = (2,3,5,7,11,13,17,19,23,29);
var
r : NativeUint;
begin
result := 1;
repeat
r := p DIV 10;
result := result*smlPrimes[p-10*r];
p := r;
until r = 0;
end;
{$align 32}
var
IsMod18 : array[0..(1000 DIV 18)*18] of boolean;
procedure OneRun;
var
{$align 32}
p1 : Uint64;
pr1,pr2,pr3,prLimit :nativeUInt;
cnt,prCnt : NativeUint;
begin
pr1 := 0;
pr2 := 0;
prCnt := 0;
prLimit := 10*1000*1000;
repeat
inc(prCnt);
pr3 := pr2;
pr2 := pr1;
pr1 := nextprime;
until pr1 > prLimit;
prLimit *= 10;
cnt := 0;
repeat
inc(prCnt);
if IsMod18[pr2-pr3] then
begin
p1 := Convert2Digits10(pr3);
if Convert2Digits10(pr2) = p1 then
if IsMod18[pr1-pr2] then
begin
if Convert2Digits10(pr1) =p1 then
begin
inc(cnt);
IF cnt <= 25 then
OutIn(cnt,pr1);
end
end
end;
if pr1 >=prLimit then
prlimit:= OutByPot10(cnt,prlimit);
pr3 := pr2;
pr2 := pr1;
pr1 := nextprime;
until pr2 > limit;
writeln(' prime count ',prCnt);
writeln(' last primes ',pr3:12,pr2:12,pr1:12);
end;
var
j :Int32;
Begin
preSieveInit;
sievePrimesInit;
InitPrime;
j := 0;
while j < High(IsMod18)do
Begin
IsMod18[j] := true;
j += 18;
end;
OneRun;
end.

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@ -0,0 +1,63 @@
package main
import (
"fmt"
"rcu"
)
func main() {
const limit = 1e10
primes := rcu.Primes(limit)
var orm25 []int
j := int(1e9)
count := 0
var counts []int
for i := 0; i < len(primes)-2; i++ {
p1 := primes[i]
p2 := primes[i+1]
p3 := primes[i+2]
if (p2-p1)%18 != 0 || (p3-p2)%18 != 0 {
continue
}
key1 := 1
for _, dig := range rcu.Digits(p1, 10) {
key1 *= primes[dig]
}
key2 := 1
for _, dig := range rcu.Digits(p2, 10) {
key2 *= primes[dig]
}
if key1 != key2 {
continue
}
key3 := 1
for _, dig := range rcu.Digits(p3, 10) {
key3 *= primes[dig]
}
if key2 == key3 {
if count < 25 {
orm25 = append(orm25, p1)
}
if p1 >= j {
counts = append(counts, count)
j *= 10
}
count++
}
}
counts = append(counts, count)
fmt.Println("Smallest members of first 25 Ormiston triples:")
for i := 0; i < 25; i++ {
fmt.Printf("%8v ", orm25[i])
if (i+1)%5 == 0 {
fmt.Println()
}
}
fmt.Println()
j = int(1e9)
for i := 0; i < len(counts); i++ {
fmt.Printf("%s Ormiston triples before %s\n", rcu.Commatize(counts[i]), rcu.Commatize(j))
j *= 10
fmt.Println()
}
}

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@ -0,0 +1,30 @@
import Data.Numbers.Primes (primes)
import Data.List (sort)
--------------------- ORMISTON TRIPLES -------------------
ormistons :: [(Integer, Integer, Integer)]
ormistons =
concat $ zipWith3
(\(dx, x) (dy, y) (dz, z)
-> [(x, y, z) | dx == dy && dx == dz])
primeDigits
(tail primeDigits)
(drop 2 primeDigits)
primeDigits :: [(Integer, Integer)]
primeDigits = ((,) =<< read . sort . show) <$> primes
--------------------------- TEST -------------------------
main :: IO ()
main = do
putStrLn "First 25 Ormistons:"
mapM_ print $ take 25 ormistons
putStrLn "\nCount of Ormistons up to 10^8:"
let limit = 10^8
print $ length $
takeWhile (\(_, _, c) -> c <= limit) ormistons

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@ -0,0 +1,9 @@
omt=: (#~ isorm) _4 p: (#~ isorm) i.&.(p:inv) 1e9
#omt NB. number of ormiston triples less than a billion
368
5 5$omt NB. first prime of the first 25 triples.
11117123 12980783 14964017 32638213 32964341
33539783 35868013 44058013 46103237 48015013
50324237 52402783 58005239 60601237 61395239
74699789 76012879 78163123 80905879 81966341
82324237 82523017 83279783 86050781 92514341

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@ -0,0 +1,16 @@
using Primes
const dig = zeros(Int, 10)
const primes10B = primes(10_000_000_000)
const sort10B = map(n -> evalpoly(10, sort!(digits!(dig, n))), primes10B)
const ormiston_indices = filter(i -> sort10B[i] == sort10B[i + 1] == sort10B[i + 2],
firstindex(sort10B):lastindex(sort10B) - 2)
println("First 25 Ormiston triples:")
for i in 1:25
println(primes10B[ormiston_indices[i]:ormiston_indices[i]+2])
end
println("\nOrmiston triples before 1 billion: ",
count(t -> primes10B[t] < 1_000_000_000, ormiston_indices))
println("Ormiston triples before 10 billion: ", length(ormiston_indices))

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@ -0,0 +1,93 @@
import std/[algorithm, bitops, math, strformat, strutils]
type Sieve = object
data: seq[byte]
func `[]`(sieve: Sieve; idx: Positive): bool =
## Return value of element at index "idx".
let idx = idx shr 1
let iByte = idx shr 3
let iBit = idx and 7
result = sieve.data[iByte].testBit(iBit)
func `[]=`(sieve: var Sieve; idx: Positive; val: bool) =
## Set value of element at index "idx".
let idx = idx shr 1
let iByte = idx shr 3
let iBit = idx and 7
if val: sieve.data[iByte].setBit(iBit)
else: sieve.data[iByte].clearBit(iBit)
func initSieve(lim: Positive): Sieve =
## Initialize a sieve from 2 to "lim".
result.data = newSeq[byte]((lim + 16) shr 4)
result[1] = true
for n in countup(3, sqrt(lim.toFloat).int, 2):
if not result[n]:
for k in countup(n * n, lim, 2 * n):
result[k] = true
func isPrime(sieve: Sieve; n: int): bool =
## Return true if "n" is prime.
result = if (n and 1) == 0: n == 2 else: not sieve[n]
func nextPrime(sieve: Sieve; n: int): int =
## Return next prime greater than "n".
result = n
while true:
inc result
if sieve.isPrime(result):
return
func digits(n: Positive): seq[byte] =
## Return the sorted list of digits of "n".
var n = n.Natural
while n != 0:
result.add byte(n mod 10)
n = n div 10
result.sort()
proc main() =
const N = 10_000_000_000
let sieve = initSieve(N)
echo "Smallest member of the first 25 Ormiston triples:"
var count = 0
var limit = N div 10
var p1 = 2
while true:
if p1 >= limit:
echo &"Number of Ormiston pairs below {insertSep($limit)}: {count}"
limit *= 10
if limit > N: break
# Check p1 and p2.
let p2 = sieve.nextPrime(p1)
if (p2 - p1) mod 18 != 0:
p1 = p2
continue
# Check p2 and p3.
let p3 = sieve.nextPrime(p2)
if (p3 - p2) mod 18 != 0:
p1 = p3 # Skip p2.
continue
# Check p1.digits and p2.digits.
let d1 = p1.digits
if p2.digits != d1:
p1 = p2
continue
# Check p1.digits and p3.digits.
if p3.digits != d1:
p1 = p3 # Skip p2.
continue
# Ormiston triple found.
inc count
if count <= 25:
stdout.write &"{p1:8}"
stdout.write if count mod 5 == 0: '\n' else: ' '
if count == 25: echo()
# Try next.
p1 = p2
main()

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@ -0,0 +1,23 @@
use strict;
use warnings;
use feature 'say';
use ntheory <primes vecfirstidx>;
my(@O,$pairs);
my @primes = @{ primes(1,1e8) };
my @A = map { join '', sort split '', $_ } @primes;
for (1..$#primes-2) { push @O, $_ if $A[$_] eq $A[$_+1] and $A[$_] eq $A[$_+2] }
say "First 25 Ormiston triples:";
$pairs .= sprintf "%8d, ", $primes[$_] for @O[0..24];
$pairs =~ s/, $//;
say $pairs =~ s/.{50}\K/\n/gr;
for (
[1e8, 'one hundred million'],
[1e9, 'one billion'],
) {
my($limit,$text) = @$_;
my $i = vecfirstidx { $primes[$_] >= $limit } @O;
printf "%3d Ormiston triples before %s\n", $i, $text;
}

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@ -0,0 +1,108 @@
(phixonline)-->
<span style="color: #000080;font-style:italic;">--
-- demo\rosetta\Ormiston_triplets.exw
-- ==================================
--
-- Uses a segmented sieve, which is about half the speed of get_primes_le(), but uses far less memory.
-- If permited, get_primes_le(1e10) would generate a result of 455,052,511 primes, more than 32 bit
-- can cope with, and use over 6GB of ram, and take about 11mins 44s, that is on this box at least,
-- whereas this processes them on-the-fly, and only uses about 6MB of memory (ie 0.1% of 6GB).
--</span>
<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</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: #008080;">procedure</span> <span style="color: #000000;">ormiston_triplets</span><span style="color: #0000FF;">(</span><span style="color: #004080;">atom</span> <span style="color: #000000;">limit</span><span style="color: #0000FF;">)</span>
<span style="color: #000080;font-style:italic;">// Generate primes using the segmented sieve of Eratosthenes.
// credit: https://gist.github.com/kimwalisch/3dc39786fab8d5b34fee</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">segment_size</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">floor</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">sqrt</span><span style="color: #0000FF;">(</span><span style="color: #000000;">limit</span><span style="color: #0000FF;">)),</span>
<span style="color: #000000;">count</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">i</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">3</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">s</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">3</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">triplen</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">1</span>
<span style="color: #004080;">atom</span> <span style="color: #000000;">p1</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">2</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">p2</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">n</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">3</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">nc</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">min</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1e9</span><span style="color: #0000FF;">,</span><span style="color: #000000;">limit</span><span style="color: #0000FF;">),</span> <span style="color: #000000;">low</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">t1</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">time</span><span style="color: #0000FF;">()+</span><span style="color: #000000;">1</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">isprime</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #004600;">true</span><span style="color: #0000FF;">,</span><span style="color: #000000;">segment_size</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">),</span>
<span style="color: #000000;">primes</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{},</span>
<span style="color: #000000;">multiples</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{},</span>
<span style="color: #000000;">orm25</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #000000;">0</span><span style="color: #0000FF;">,</span><span style="color: #000000;">25</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">while</span> <span style="color: #000000;">low</span><span style="color: #0000FF;"><=</span><span style="color: #000000;">limit</span> <span style="color: #008080;">do</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">sieve</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #004600;">true</span><span style="color: #0000FF;">,</span><span style="color: #000000;">segment_size</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">if</span> <span style="color: #7060A8;">time</span><span style="color: #0000FF;">()></span><span style="color: #000000;">t1</span> <span style="color: #008080;">then</span>
<span style="color: #7060A8;">progress</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"Processing %,d/%,d (%3.2f%%)\r"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">low</span><span style="color: #0000FF;">,</span><span style="color: #000000;">limit</span><span style="color: #0000FF;">,(</span><span style="color: #000000;">low</span><span style="color: #0000FF;">/</span><span style="color: #000000;">limit</span><span style="color: #0000FF;">)*</span><span style="color: #000000;">100</span><span style="color: #0000FF;">})</span>
<span style="color: #000000;">t1</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">time</span><span style="color: #0000FF;">()+</span><span style="color: #000000;">1</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #000080;font-style:italic;">// current segment = [low, high]</span>
<span style="color: #004080;">atom</span> <span style="color: #000000;">high</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">min</span><span style="color: #0000FF;">(</span><span style="color: #000000;">low</span><span style="color: #0000FF;">+</span><span style="color: #000000;">segment_size</span><span style="color: #0000FF;">,</span><span style="color: #000000;">limit</span><span style="color: #0000FF;">)</span>
<span style="color: #000080;font-style:italic;">// generate sieving primes using simple sieve of Eratosthenes</span>
<span style="color: #008080;">while</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">*</span><span style="color: #000000;">i</span><span style="color: #0000FF;"><=</span><span style="color: #7060A8;">min</span><span style="color: #0000FF;">(</span><span style="color: #000000;">high</span><span style="color: #0000FF;">,</span><span style="color: #000000;">segment_size</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">isprime</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: #008080;">then</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">j</span><span style="color: #0000FF;">=</span><span style="color: #000000;">i</span><span style="color: #0000FF;">*</span><span style="color: #000000;">i</span> <span style="color: #008080;">to</span> <span style="color: #000000;">segment_size</span> <span style="color: #008080;">by</span> <span style="color: #000000;">i</span> <span style="color: #008080;">do</span>
<span style="color: #000000;">isprime</span><span style="color: #0000FF;">[</span><span style="color: #000000;">j</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: #004600;">false</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #000000;">i</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">2</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #000080;font-style:italic;">// initialize sieving primes for segmented sieve</span>
<span style="color: #008080;">while</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">*</span><span style="color: #000000;">s</span><span style="color: #0000FF;"><=</span><span style="color: #000000;">high</span> <span style="color: #008080;">do</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">isprime</span><span style="color: #0000FF;">[</span><span style="color: #000000;">s</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span> <span style="color: #008080;">then</span>
<span style="color: #000000;">primes</span> <span style="color: #0000FF;">&=</span> <span style="color: #000000;">s</span>
<span style="color: #000000;">multiples</span> <span style="color: #0000FF;">&=</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">*</span><span style="color: #000000;">s</span><span style="color: #0000FF;">-</span><span style="color: #000000;">low</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #000000;">s</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">2</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #000080;font-style:italic;">// sieve the current segment</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">mi</span><span style="color: #0000FF;">,</span><span style="color: #000000;">j</span> <span style="color: #008080;">in</span> <span style="color: #000000;">multiples</span> <span style="color: #008080;">do</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">k</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">primes</span><span style="color: #0000FF;">[</span><span style="color: #000000;">mi</span><span style="color: #0000FF;">]*</span><span style="color: #000000;">2</span>
<span style="color: #008080;">while</span> <span style="color: #000000;">j</span><span style="color: #0000FF;"><</span><span style="color: #000000;">segment_size</span> <span style="color: #008080;">do</span>
<span style="color: #000000;">sieve</span><span style="color: #0000FF;">[</span><span style="color: #000000;">j</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: #004600;">false</span>
<span style="color: #000000;">j</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">k</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #000000;">multiples</span><span style="color: #0000FF;">[</span><span style="color: #000000;">mi</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">j</span> <span style="color: #0000FF;">-</span> <span style="color: #000000;">segment_size</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">while</span> <span style="color: #000000;">n</span><span style="color: #0000FF;"><=</span><span style="color: #000000;">high</span> <span style="color: #008080;">do</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">sieve</span><span style="color: #0000FF;">[</span><span style="color: #000000;">n</span><span style="color: #0000FF;">-</span><span style="color: #000000;">low</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span> <span style="color: #008080;">then</span> <span style="color: #000080;font-style:italic;">// n is a prime</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">triplen</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">then</span>
<span style="color: #008080;">if</span> <span style="color: #7060A8;">remainder</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">-</span><span style="color: #000000;">p1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">18</span><span style="color: #0000FF;">)=</span><span style="color: #000000;">0</span>
<span style="color: #008080;">and</span> <span style="color: #7060A8;">sort</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">sprint</span><span style="color: #0000FF;">(</span><span style="color: #000000;">p1</span><span style="color: #0000FF;">))=</span><span style="color: #7060A8;">sort</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">sprint</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">))</span> <span style="color: #008080;">then</span>
<span style="color: #000000;">p2</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">n</span>
<span style="color: #000000;">triplen</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">2</span>
<span style="color: #008080;">else</span>
<span style="color: #000000;">p1</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">n</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">elsif</span> <span style="color: #000000;">triplen</span><span style="color: #0000FF;">=</span><span style="color: #000000;">2</span>
<span style="color: #008080;">and</span> <span style="color: #7060A8;">remainder</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">-</span><span style="color: #000000;">p2</span><span style="color: #0000FF;">,</span><span style="color: #000000;">18</span><span style="color: #0000FF;">)=</span><span style="color: #000000;">0</span>
<span style="color: #008080;">and</span> <span style="color: #7060A8;">sort</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">sprint</span><span style="color: #0000FF;">(</span><span style="color: #000000;">p2</span><span style="color: #0000FF;">))=</span><span style="color: #7060A8;">sort</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">sprint</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">))</span> <span style="color: #008080;">then</span>
<span style="color: #000080;font-style:italic;">-- triplet found!</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">p1</span><span style="color: #0000FF;">>=</span><span style="color: #000000;">nc</span> <span style="color: #008080;">then</span>
<span style="color: #004080;">string</span> <span style="color: #000000;">e</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">elapsed_short</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>
<span style="color: #7060A8;">progress</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"%,d Ormiston triplets before %,d (%s)\n"</span><span style="color: #0000FF;">,</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">count</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">nc</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">e</span><span style="color: #0000FF;">})</span>
<span style="color: #000000;">nc</span> <span style="color: #0000FF;">*=</span> <span style="color: #000000;">10</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #000000;">count</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">1</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">count</span><span style="color: #0000FF;"><=</span><span style="color: #000000;">25</span> <span style="color: #008080;">then</span>
<span style="color: #000000;">orm25</span><span style="color: #0000FF;">[</span><span style="color: #000000;">count</span><span style="color: #0000FF;">]</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: #000000;">p1</span><span style="color: #0000FF;">})</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">count</span><span style="color: #0000FF;">=</span><span style="color: #000000;">25</span> <span style="color: #008080;">then</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;">"Smallest members of first 25 Ormiston triplets:\n%s\n"</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">join_by</span><span style="color: #0000FF;">(</span><span style="color: #000000;">orm25</span><span style="color: #0000FF;">,</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">5</span><span style="color: #0000FF;">))</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #000080;font-style:italic;">-- overlapping (and leave triplen set to 2):</span>
<span style="color: #000000;">p1</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">p2</span>
<span style="color: #000000;">p2</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">n</span>
<span style="color: #000080;font-style:italic;">-- (for disjoint-only just set triplen to 0)</span>
<span style="color: #008080;">else</span>
<span style="color: #000000;">p1</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">n</span>
<span style="color: #000000;">triplen</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">1</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #000000;">n</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">2</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #000000;">low</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">segment_size</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #004080;">string</span> <span style="color: #000000;">e</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">elapsed_short</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>
<span style="color: #7060A8;">progress</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"%,d Ormiston triplets before %,d (%s)\n"</span><span style="color: #0000FF;">,</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">count</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">nc</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">e</span><span style="color: #0000FF;">})</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #000000;">ormiston_triplets</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">iff</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">platform</span><span style="color: #0000FF;">()=</span><span style="color: #004600;">JS</span><span style="color: #0000FF;">?</span><span style="color: #000000;">1e8</span><span style="color: #0000FF;">:</span><span style="color: #000000;">1e9</span><span style="color: #0000FF;">))</span>
<!--

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@ -0,0 +1,44 @@
(notonline)-->
<span style="color: #7060A8;">requires</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"1.0.3"</span><span style="color: #0000FF;">)</span>
<span style="color: #7060A8;">requires</span><span style="color: #0000FF;">(</span><span style="color: #004600;">WINDOWS</span><span style="color: #0000FF;">)</span>
<span style="color: #7060A8;">requires</span><span style="color: #0000FF;">(</span><span style="color: #000000;">64</span><span style="color: #0000FF;">,</span><span style="color: #004600;">true</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">include</span> <span style="color: #000000;">builtins</span><span style="color: #0000FF;">/</span><span style="color: #000000;">primesieve</span><span style="color: #0000FF;">.</span><span style="color: #000000;">e</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;">t1</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">time</span><span style="color: #0000FF;">()+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span>
<span style="color: #000000;">p</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">primesieve_next_prime</span><span style="color: #0000FF;">(),</span>
<span style="color: #000000;">p1</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">p</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">p2</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">count</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">nc</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">1e9</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">orm25</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #000000;">0</span><span style="color: #0000FF;">,</span><span style="color: #000000;">25</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">procedure</span> <span style="color: #000000;">showt</span><span style="color: #0000FF;">()</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">count</span><span style="color: #0000FF;">=</span><span style="color: #000000;">25</span> <span style="color: #008080;">then</span>
<span style="color: #7060A8;">progress</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"Smallest members of first 25 Ormiston triplets:\n"</span><span style="color: #0000FF;">)</span>
<span style="color: #7060A8;">progress</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"%s\n"</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">join_by</span><span style="color: #0000FF;">(</span><span style="color: #000000;">orm25</span><span style="color: #0000FF;">,</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">5</span><span style="color: #0000FF;">))</span>
<span style="color: #008080;">else</span>
<span style="color: #004080;">string</span> <span style="color: #000000;">e</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">elapsed_short</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>
<span style="color: #7060A8;">progress</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"%,6d Ormiston triplets before %,d (%s)\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">count</span><span style="color: #0000FF;">,</span><span style="color: #000000;">nc</span><span style="color: #0000FF;">,</span><span style="color: #000000;">e</span><span style="color: #0000FF;">})</span>
<span style="color: #000000;">nc</span> <span style="color: #0000FF;">*=</span> <span style="color: #000000;">10</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #008080;">while</span> <span style="color: #000000;">p</span><span style="color: #0000FF;"><</span><span style="color: #000000;">1e10</span> <span style="color: #008080;">do</span>
<span style="color: #000000;">p2</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">p1</span>
<span style="color: #000000;">p1</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">p</span>
<span style="color: #000000;">p</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">primesieve_next_prime</span><span style="color: #0000FF;">()</span>
<span style="color: #008080;">if</span> <span style="color: #7060A8;">remainder</span><span style="color: #0000FF;">(</span><span style="color: #000000;">p</span><span style="color: #0000FF;">-</span><span style="color: #000000;">p1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">18</span><span style="color: #0000FF;">)=</span><span style="color: #000000;">0</span>
<span style="color: #008080;">and</span> <span style="color: #7060A8;">remainder</span><span style="color: #0000FF;">(</span><span style="color: #000000;">p1</span><span style="color: #0000FF;">-</span><span style="color: #000000;">p2</span><span style="color: #0000FF;">,</span><span style="color: #000000;">18</span><span style="color: #0000FF;">)=</span><span style="color: #000000;">0</span> <span style="color: #008080;">then</span>
<span style="color: #004080;">string</span> <span style="color: #000000;">s</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">sort</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">sprint</span><span style="color: #0000FF;">(</span><span style="color: #000000;">p</span><span style="color: #0000FF;">))</span>
<span style="color: #008080;">if</span> <span style="color: #7060A8;">sort</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">sprint</span><span style="color: #0000FF;">(</span><span style="color: #000000;">p1</span><span style="color: #0000FF;">))=</span><span style="color: #000000;">s</span>
<span style="color: #008080;">and</span> <span style="color: #7060A8;">sort</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">sprint</span><span style="color: #0000FF;">(</span><span style="color: #000000;">p2</span><span style="color: #0000FF;">))=</span><span style="color: #000000;">s</span> <span style="color: #008080;">then</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">p</span><span style="color: #0000FF;">>=</span><span style="color: #000000;">nc</span> <span style="color: #008080;">then</span> <span style="color: #000000;">showt</span><span style="color: #0000FF;">()</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #000000;">count</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">1</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">count</span><span style="color: #0000FF;"><=</span><span style="color: #000000;">25</span> <span style="color: #008080;">then</span>
<span style="color: #000000;">orm25</span><span style="color: #0000FF;">[</span><span style="color: #000000;">count</span><span style="color: #0000FF;">]</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: #000000;">p2</span><span style="color: #0000FF;">})</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">count</span><span style="color: #0000FF;">=</span><span style="color: #000000;">25</span> <span style="color: #008080;">then</span> <span style="color: #000000;">showt</span><span style="color: #0000FF;">()</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">elsif</span> <span style="color: #7060A8;">time</span><span style="color: #0000FF;">()></span><span style="color: #000000;">t1</span> <span style="color: #008080;">then</span>
<span style="color: #7060A8;">progress</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"%,d\r"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">p</span><span style="color: #0000FF;">})</span>
<span style="color: #000000;">t1</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">time</span><span style="color: #0000FF;">()+</span><span style="color: #000000;">1</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #000000;">showt</span><span style="color: #0000FF;">()</span>
<!--

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@ -0,0 +1,59 @@
import textwrap
from itertools import pairwise
from typing import Iterator
from typing import List
import primesieve
def primes() -> Iterator[int]:
it = primesieve.Iterator()
while True:
yield it.next_prime()
def triplewise(iterable):
for (a, _), (b, c) in pairwise(pairwise(iterable)):
yield a, b, c
def is_anagram(a: int, b: int, c: int) -> bool:
return sorted(str(a)) == sorted(str(b)) == sorted(str(c))
def up_to_one_billion() -> int:
count = 0
for triple in triplewise(primes()):
if is_anagram(*triple):
count += 1
if triple[2] >= 1_000_000_000:
break
return count
def up_to_ten_billion() -> int:
count = 0
for triple in triplewise(primes()):
if is_anagram(*triple):
count += 1
if triple[2] >= 10_000_000_000:
break
return count
def first_25() -> List[int]:
rv: List[int] = []
for triple in triplewise(primes()):
if is_anagram(*triple):
rv.append(triple[0])
if len(rv) >= 25:
break
return rv
if __name__ == "__main__":
print("Smallest members of first 25 Ormiston triples:")
print(textwrap.fill(" ".join(str(i) for i in first_25())), "\n")
print(up_to_one_billion(), "Ormiston triples before 1,000,000,000")
print(up_to_ten_billion(), "Ormiston triples before 10,000,000,000")

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@ -0,0 +1,10 @@
use Lingua::EN::Numbers;
use List::Divvy;
my @primes = lazy (^).hyper.grep( &is-prime ).map: { $_ => .comb.sort.join };
my @Ormistons = @primes.kv.map: { $^value.key if $^value.value eq @primes[$^key+1].value eq @primes[$^key+2].value};
say "First twenty-five Ormiston triples:";
say @Ormistons[^25].batch(5)».join(', ').join: "\n";
say '';
say +@Ormistons.&before( *[0] > $_ ) ~ " Ormiston triples before " ~ .Int.&cardinal for 1e8, 1e9;

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@ -0,0 +1,40 @@
import "./math" for Int
import "./fmt" for Fmt
var limit = 1e10
var primes = Int.segmentedSieve(limit, 128 * 1024)
var orm25 = []
var j = limit/10
var count = 0
var counts = []
for (i in 0...primes.count-2) {
var p1 = primes[i]
var p2 = primes[i+1]
var p3 = primes[i+2]
if ((p2 - p1) % 18 != 0 || (p3 - p2) % 18 != 0) continue
var key1 = 1
for (dig in Int.digits(p1)) key1 = key1 * primes[dig]
var key2 = 1
for (dig in Int.digits(p2)) key2 = key2 * primes[dig]
if (key1 != key2) continue
var key3 = 1
for (dig in Int.digits(p3)) key3 = key3 * primes[dig]
if (key2 == key3) {
if (count < 25) orm25.add(p1)
if (p1 >= j) {
counts.add(count)
j = j * 10
}
count = count + 1
}
}
counts.add(count)
System.print("Smallest members of first 25 Ormiston triples:")
Fmt.tprint("$,10d ", orm25, 5)
System.print()
j = limit/10
for (i in 0...counts.count) {
Fmt.print("$,d Ormiston triples before $,d", counts[i], j)
j = j * 10
System.print()
}

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@ -0,0 +1,45 @@
import "./psieve" for Primes
import "./math" for Int
import "./fmt" for Fmt
var limit = 1e10
var digitPrimes = Int.primeSieve(30)
var it = Primes.iter()
var orm25 = []
var j = limit/10
var count = 0
var counts = []
var p1 = it.next
var p2 = it.next
var p3 = it.next
while (true) {
p1 = p2
p2 = p3
p3 = it.next
if ((p2 - p1) % 18 != 0 || (p3 - p2) % 18 != 0) continue
var key1 = 1
for (dig in Int.digits(p1)) key1 = key1 * digitPrimes[dig]
var key2 = 1
for (dig in Int.digits(p2)) key2 = key2 * digitPrimes[dig]
if (key1 != key2) continue
var key3 = 1
for (dig in Int.digits(p3)) key3 = key3 * digitPrimes[dig]
if (key2 == key3) {
if (count < 25) orm25.add(p1)
if (p1 >= j) {
counts.add(count)
if (j == limit) break
j = j * 10
}
count = count + 1
}
}
System.print("Smallest members of first 25 Ormiston triples:")
Fmt.tprint("$,10d ", orm25, 5)
System.print()
j = limit/10
for (i in 0...counts.count) {
Fmt.print("$,d Ormiston triples before $,d", counts[i], j)
j = j * 10
System.print()
}

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@ -0,0 +1,54 @@
char Sieve;
proc MakeSieve(Size); \Make prime number sieve
int Size, Prime, I, K;
[Size:= Size/2; \ignore even numbers
Sieve:= MAlloc(Size+1); \(XPL0's heap only provides 64 MB)
for I:= 0 to Size do \set Sieve flags all true
Sieve(I):= true;
for I:= 0 to Size do
if Sieve(I) then \found a prime, which is equal to
[Prime:= I + I + 3; \ twice the index + 3
K:= I + Prime; \first multiple to strike off
while K <= Size do \strike off all multiples
[Sieve(K):= false;
K:= K + Prime;
];
];
];
func GetSig(N); \Return signature of N
\A "signature" is the count of each digit in N packed into a 32-bit word
int N, Sig;
[Sig:= 0;
repeat N:= N/10;
Sig:= Sig + 1<<(rem(0)*3);
until N = 0;
return Sig;
];
def Limit = 1_000_000_000;
int Cnt, N, N0, N1, Sig, Sig0, Sig1;
[MakeSieve(Limit);
Text(0, "Smallest members of first 25 Ormiston triples:^m^j");
Cnt:= 0; N0:= 0; N1:= 0; Sig0:= 0; Sig1:= 0; N:= 3;
Format(10, 0);
loop [if Sieve(N>>1-1) then \is prime
[Sig:= GetSig(N);
if Sig = Sig1 and Sig = Sig0 then
[Cnt:= Cnt+1;
if Cnt <= 25 then
[RlOut(0, float(N0));
if rem(Cnt/5) = 0 then CrLf(0);
];
];
Sig0:= Sig1; Sig1:= Sig;
N0:= N1; N1:= N;
];
if N >= Limit then
[IntOut(0, Cnt);
Text(0, " Ormiston triples before one billion.^m^j");
quit;
];
N:= N+2;
];
]