Smallest number k such that k+2^m is composite for all m less than k: Difference between revisions

=={{header|Go}}==

{{trans|Wren}}

{{libheader|GMP(Go wrapper)}}

Takes around 2.2 seconds though faster than using Go's native big.Int type which takes 6.2 seconds.

<lang go>package main

import (

"fmt"

big "github.com/ncw/gmp"

)

// returns true if k is a sequence member, false otherwise

func a(k int64) bool {

if k == 1 {

return false

}

bk := big.NewInt(k)

for m := uint(1); m < uint(k); m++ {

n := big.NewInt(1)

n.Lsh(n, m)

n.Add(n, bk)

if n.ProbablyPrime(15) {

return false

}

}

return true

}

func main() {

count := 0

k := int64(1)

for count < 5 {

if a(k) {

fmt.Printf("%d ", k)

count++

}

k += 2

}

fmt.Println()

}</lang>

{{out}}

<pre>

773 2131 2491 4471 5101

</pre>