Repunit primes: Difference between revisions

{{libheader|GMP}}

{{libheader|Primesieve}}

#include <iomanip>

#include <iostream>

std::cout << '\n';

}

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=={{header|F_Sharp|F#}}==

This task uses [http://www.rosettacode.org/wiki/Extensible_prime_generator#The_functions Extensible Prime Generator (F#)]

// Repunit primes. Nigel Galloway: January 24th., 2022

let rUnitP(b:int)=let b=bigint b in primes32()|>Seq.takeWhile((>)1000)|>Seq.map(fun n->(n,((b**n)-1I)/(b-1I)))|>Seq.filter(fun(_,n)->Open.Numeric.Primes.MillerRabin.IsProbablePrime &n)|>Seq.map fst

[2..16]|>List.iter(fun n->printf $"Base %d{n}: "; rUnitP(n)|>Seq.iter(printf "%d "); printfn "")

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<pre>

{{libheader|Go-rcu}}

Took 11 minutes 25 seconds which is much the same as Wren's GMP wrapper.

import (

fmt.Printf("Base %2d: %v\n", b, rPrimes)

}

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=={{header|Julia}}==

repunitprimeinbase(n, base) = isprime(evalpoly(BigInt(base), [1 for _ in 1:n]))

println(rpad("Base $b:", 9), filter(n -> repunitprimeinbase(n, b), 1:2700))

end

<pre>

Base 2: [2, 3, 5, 7, 13, 17, 19, 31, 61, 89, 107, 127, 521, 607, 1279, 2203, 2281]

=={{header|Mathematica}}/{{header|Wolfram Language}}==

RepUnitPrimeQ[b_][n_] := PrimeQ[FromDigits[ConstantArray[1, n], b]]

ClearAll[RepUnitPrimeQ]

{b, 2, 16}

]

Searching bases 2–16 for repunits of size 2700:

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=={{header|Perl}}==

{{libheader|ntheory}}

use warnings;

use ntheory <is_prime fromdigits>;

for my $base (2..16) {

printf "Base %2d: %s\n", $base, join ' ', grep { is_prime $_ and is_prime fromdigits(('1'x$_), $base) and " $_" } 1..$limit

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<pre>Repunit prime digits (up to 1000) in:

=={{header|Phix}}==

<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>

<span style="color: #008080;">include</span> <span style="color: #004080;">mpfr</span><span style="color: #0000FF;">.</span><span style="color: #000000;">e</span>

<span style="color: #008080;">end</span> <span style="color: #008080;">for</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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Note the first half (base<=16) is from a {2700,16} run and the rest (base>16) from a {1000,36} run.

=={{header|Python}}==

for b in range(2, 17):

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<pre>2 [2, 3, 5, 7, 13, 17, 19, 31, 61, 89, 107, 127, 521, 607]

=={{header|Raku}}==

say "Repunit prime digits (up to $limit) in:";

.put for (2..16).hyper(:1batch).map: -> $base {

$base.fmt("Base %2d: ") ~ (1..$limit).grep(&is-prime).grep( (1 x *).parse-base($base).is-prime )

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<pre>Repunit prime digits (up to 2700) in:

<br />

'''Primality Test'''

(define prime<probably>?

(lambda (n)

(or (= n 2)

(and (odd? n)

'''The Task'''

(define repunit_primes

(lambda (base limit)

(do ((base 2 (1+ base)))

((> base max-base))

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<pre>

=={{header|Sidef}}==

say "Repunit prime digits (up to #{limit}) in:"

printf("Base %2d: %s\n", n,

{|k| is_prime((n**k - 1) / (n-1)) }.grep(1..limit))

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<pre>

Still takes a while - 11 minutes 20 seconds to get up to base 36 with a limit of 2700.

import "./gmp" for Mpz

}

Fmt.print("Base $2d: $n", b, rPrimes)

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