A316568 Largest k such that 1^2 + n, 2^2 + n, ..., k^2 + n are composite.

0, 0, 1, 0, 5, 0, 1, 2, 1, 0, 5, 0, 1, 2, 1, 0, 5, 0, 1, 2, 3, 0, 5, 6, 1, 8, 1, 0, 11, 0, 3, 2, 1, 2, 5, 0, 1, 2, 1, 0, 23, 0, 1, 2, 3, 0, 5, 4, 1, 2, 3, 0, 5, 4, 1, 8, 1, 0, 17, 0, 5, 2, 1, 2, 5, 0, 1, 8, 1, 0, 5, 0, 3, 2, 1, 4, 5, 0, 1, 2, 3, 0, 11, 4, 1, 8, 3, 0, 11, 6, 3, 2, 1, 2, 5, 0, 1, 2, 1, 0

Offset: 1

Author

Seiichi Manyama, Jul 06 2018

Keywords

• nonn

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A085099.

Programs

Mathematica

lk[n_]:=Module[{k=1},While[CompositeQ[k^2+n],k++];k-1]; Array[lk,100] (* Harvey P. Dale, Aug 04 2022 *)

Formula

a(n) = A085099(n) - 1.