A032494 Numbers k such that 235*2^k+1 is prime.

2, 4, 8, 10, 12, 14, 20, 22, 24, 32, 56, 76, 84, 86, 92, 118, 164, 382, 604, 1148, 1900, 2440, 2554, 2798, 3160, 6092, 7142, 14044, 14782, 21056, 24852, 29084, 44252, 46022, 101318, 294216, 412366, 493738, 769740, 923728, 1206136, 1596836, 2023486

Offset

1,1

Links

Table of n, a(n) for n=1..43.

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[235*2^# + 1] & ] (* Robert Price, Dec 19 2018 *)

Prog

(PARI) is(n)=ispseudoprime(235*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A132190 A155037 A001770 * A125953 A373490 A308357

Adjacent sequences: A032491 A032492 A032493 * A032495 A032496 A032497

Keyword

nonn,hard,more

Author

N. J. A. Sloane.

Extensions

a(36)-a(42) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 19 2018

a(43) from Jeppe Stig Nielsen, May 31 2020

Status

approved