A032496 Numbers k such that 239*2^k+1 is prime.

1, 3, 5, 7, 17, 29, 31, 89, 135, 229, 257, 305, 493, 781, 811, 1177, 1315, 1709, 2267, 5283, 6109, 7763, 7923, 16481, 18457, 29187, 39487, 53393, 59905, 76267, 109325, 278595, 307745, 547433, 651413, 1072433, 1936025, 2076663, 4795541

Offset

1,2

Links

Table of n, a(n) for n=1..39.

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[239*2^# + 1] & ] (* Robert Price, Dec 20 2018 *)

Prog

(PARI) is(n)=ispseudoprime(239*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A141772 A220454 A257592 * A002092 A274906 A296422

Adjacent sequences: A032493 A032494 A032495 * A032497 A032498 A032499

Keyword

nonn,hard,more

Author

N. J. A. Sloane.

Extensions

a(30)-a(38) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 20 2018

a(39) from Jeppe Stig Nielsen, May 30 2020

Duplicate term a(29)=59905 removed by Georg Fischer, Mar 18 2022

a(39) from Jeppe Stig Nielsen, Dec 21 2024

Status

approved