A032454 Numbers k such that 155*2^k+1 is prime.

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

Links

Table of n, a(n) for n=1..33.

Ray Ballinger, Proth Search Page

Ray Ballinger and 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[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

Adjacent sequences: A032451 A032452 A032453 * A032455 A032456 A032457

Keyword

nonn,hard,more

Author

N. J. A. Sloane

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