A126915 Numbers k such that 1 + k^2 + k^4 + k^6 + k^8 + k^10 + k^12 + k^14 + k^16 + k^18 + k^20 + k^21 is prime.

2, 6, 12, 60, 68, 138, 270, 446, 488, 620, 656, 798, 872, 942, 950, 1136, 1140, 1256, 1400, 1418, 1506, 1638, 1776, 1922, 1992, 2070, 2082, 2096, 2220, 2346, 2462, 2580, 2606, 2916

Offset: 1

Author

Artur Jasinski, Dec 31 2006

Keywords

• nonn
• easy

Links

• Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A049407, A124175 A124176 A124177, A124178, A124179, A124180, A124181, A126908-A126916.

Programs

Magma

[k:k in [1..3000]| IsPrime(1+k^2+k^4+k^6+k^8+k^10+k^12+k^14+k^16+ k^18+k^20 +k^21)]; // Marius A. Burtea, Feb 11 2020

Mathematica

a = {}; Do[If[PrimeQ[1 + n^2 + n^4 + n^6 + n^8 + n^10 + n^12 + n^14 + n^16 + n^18 + n^20 + n^21], AppendTo[a, n]], {n, 1, 1400}]; a

PARI

is(n)=isprime(1+n^2+n^4+n^6+n^8+n^10+n^12+n^14+n^16+n^18+n^20+n^21) \\ Charles R Greathouse IV, Jun 13 2017