login
A032503
Numbers k such that 253*2^k+1 is prime.
1
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
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
KEYWORD
nonn,hard
AUTHOR
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