A215434 Primes of form 2^k + k^2 - 1.

2, 7, 31, 1123, 1180591620717411308323, 21778071482940061661655974875633165551139, 89202980794122492566142873090593446023942979, 1569275433846670190958947355801916604025588861116008664323

Offset: 1

Author

Vincenzo Librandi, Sep 03 2012

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..11

Crossrefs

Cf. A035325, A061119, A215439.

Programs

Magma

[a: n in [0..250] | IsPrime(a) where a is 2^n+n^2-1];

Mathematica

Select[Table[2^n + n^2 - 1, {n, 0, 300}], PrimeQ]