A215439 Numbers k such that 2^k + k^2 - 1 is prime.

1, 2, 4, 10, 70, 134, 146, 190, 218, 292, 478, 7136, 15964, 19988, 100790, 111442, 181874, 202112

Offset: 1

Author

Vincenzo Librandi, Sep 03 2012

Keywords

• nonn

Comments

a(17) > 150000. - Giovanni Resta, Mar 19 2014

a(19) > 3*10^5. - Robert Price, Apr 30 2014

Crossrefs

Cf. A215434.

Programs

Magma

[n: n in [0..1000] | IsPrime(2^n+n^2-1)]

Mathematica

Select[Range[0, 9000], PrimeQ[2^# + #^2 - 1] &]

PARI

is(n)=ispseudoprime(2^n+n^2-1) \\ Charles R Greathouse IV, May 22 2017

Extensions

a(13)-a(16) from Giovanni Resta, Mar 19 2014

a(17)-a(18) from Robert Price, Apr 30 2014