A032503 Numbers k such that 253*2^k+1 is prime.

2, 4, 6, 16, 32, 48, 50, 52, 64, 66, 72, 86, 108, 130, 164, 304, 356, 482, 486, 712, 772, 834, 1196, 1508, 1552, 1600, 1754, 1858, 2228, 3562, 3900, 4834, 10400, 26736, 33700, 34276, 35860, 38152, 61256, 76828, 169312, 186218, 204140, 335828, 483768, 485188

Offset

1,1

Links

Jeppe Stig Nielsen, Table of n, a(n) for n = 1..54

Ray Ballinger, Proth Search Page

Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for k < 300

Wilfrid Keller, List of primes k.2^n - 1 for k < 300

Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime

Mathematica

Select[Range[1000], PrimeQ[253*2^# + 1] & ] (* Robert Price, Dec 20 2018 *)

Prog

(PARI) is(n)=ispseudoprime(253*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A045663 A128092 A167569 * A050838 A374512 A271842

Adjacent sequences: A032500 A032501 A032502 * A032504 A032505 A032506

Keyword

nonn,hard,changed

Author

N. J. A. Sloane.

Extensions

a(35)-a(51) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 20 2018

Terms moved from Data section to b-file, and more terms added to b-file by Jeppe Stig Nielsen, Mar 12 2020

Status

approved