login
A032492
Numbers k such that 231*2^k+1 is prime.
1
1, 4, 5, 7, 9, 11, 12, 13, 15, 27, 33, 65, 85, 89, 105, 120, 149, 161, 175, 229, 279, 295, 307, 355, 453, 528, 625, 697, 807, 831, 879, 901, 935, 988, 1265, 1432, 1645, 1761, 1899, 1939, 2497, 3101, 5176, 5181, 9809, 14025, 21765, 27333, 35271, 36717, 40935
OFFSET
1,2
LINKS
MATHEMATICA
Select[Range[1000], PrimeQ[231*2^# + 1] & ] (* Robert Price, Dec 19 2018 *)
PROG
(PARI) is(n)=ispseudoprime(231*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
Sequence in context: A191771 A267027 A267865 * A223134 A339690 A267087
KEYWORD
nonn,hard
AUTHOR
EXTENSIONS
a(51)-a(72) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 19 2018
STATUS
approved