Fermat pseudoprimes: Difference between revisions

=={{header|ALGOL 68}}==

# if a^(x-1) - 1 is divisible by x and x is not prime #

print( ( newline ) )

OD

{{out}}

<pre>

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

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

// Fermat pseudoprimes. Nigel Galloway: August 17th., 2022

let fp(a:int)=let a=bigint a in primesI()|>Seq.pairwise|>Seq.collect(fun(n,g)->seq{for n in n+1I..g-1I do if bigint.ModPow(a,n-1I,n)=1I then yield n})

{1..20}|>Seq.iter(fun n->printf $"Base %2d{n} - Up to 50000: %5d{fp n|>Seq.takeWhile((>=)50000I)|>Seq.length} First 20: ("; fp n|>Seq.take 20|>Seq.iter(printf "%A "); printfn ")")

{{out}}

<pre>

=={{header|Julia}}==

ispseudo(n, base) = !isprime(n) && BigInt(base)^(n - 1) % n == 1

println("Base ", lpad(b, 2), " up to 50000: ", lpad(length(pseudos), 5), " First 20: ", pseudos[1:20])

end

<pre>

Base 1 up to 50000: 44866 First 20: [4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 26, 27, 28, 30, 32]

=={{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: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"%2d: %s %s\n"</span><span style="color: #0000FF;">,</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">base</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">c</span><span style="color: #0000FF;">})</span>

<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>

{{out}}

<pre style="font-size: 12px">

=={{header|Raku}}==

for 1..20 -> $base {

my @pseudo = lazy (2..*).hyper.grep: { !.is-prime && (1 == expmod $base, $_ - 1, $_) }

say $base.fmt("Base %2d - Up to $threshold: ") ~ (+@pseudo.&upto: $threshold).fmt('%5d')

~ " First 20: " ~ @pseudo[^20].gist

<pre style="font-size:90%;">Base 1 - Up to 100000: 90407 First 20: (4 6 8 9 10 12 14 15 16 18 20 21 22 24 25 26 27 28 30 32)

Base 2 - Up to 100000: 78 First 20: (341 561 645 1105 1387 1729 1905 2047 2465 2701 2821 3277 4033 4369 4371 4681 5461 6601 7957 8321)

{{libheader|Wren-gmp}}

{{libheader|Wren-fmt}}

import "./gmp" for Mpz

import "./fmt" for Fmt

}

System.print()

{{out}}