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

=={{header|Wren}}==

{{libheader|Wren-gmp}}

An embedded version as, judging by the size of numbers involved, Wren-CLI (using BigInt) will be too slow for this.

Brute force approach - takes a smidge over 2 seconds.

<lang ecmascript>import "./gmp" for Mpz

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

var a = Fn.new { |k|

if (k == 1) return false

for (m in 1...k) {

var n = (Mpz.one << m) + k

if (n.probPrime(15) > 0) return false

}

return true

}

var count = 0

var k = 1

while (count < 5) {

if (a.call(k)) {

System.write("%(k) ")

count = count + 1

}

k = k + 2

}

System.print()</lang>

{{out}}

<pre>

773 2131 2491 4471 5101

</pre>