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A032454
Numbers k such that 155*2^k+1 is prime.
1
1, 7, 17, 23, 29, 31, 41, 261, 353, 437, 447, 591, 649, 677, 1253, 1301, 2449, 9313, 11749, 16661, 25173, 32887, 38761, 67973, 79557, 149423, 173833, 298679, 336951, 684887, 1199689, 2357111, 2602213
OFFSET
1,2
MATHEMATICA
Select[Range[1000], PrimeQ[155*2^# + 1] & ] (* Robert Price, Dec 18 2018 *)
PROG
(PARI) is(n)=ispseudoprime(155*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
Sequence in context: A215824 A239210 A191087 * A107643 A289363 A319040
KEYWORD
nonn,hard,more
EXTENSIONS
Extended by Hugo Pfoertner, Jul 02 2003
a(27)-a(31) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 18 2018
a(32)-a(33) from Jeppe Stig Nielsen, Mar 12 2020
STATUS
approved