A032504 Numbers k such that 255*2^k+1 is prime.

2, 5, 32, 36, 38, 41, 57, 69, 71, 72, 116, 137, 156, 197, 237, 336, 353, 489, 545, 678, 1040, 1137, 1217, 1451, 1577, 1589, 1836, 3077, 4640, 4850, 5145, 7139, 7766, 8051, 9662, 11159, 13433, 13763, 15998, 16862, 19002, 25412, 35558, 47916, 48509, 86900

Offset

1,1

Links

Jeppe Stig Nielsen, Table of n, a(n) for n = 1..67 (terms n = 1..63 from Robert Price)

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[255*2^# + 1] & ] (* Robert Price, Dec 20 2018 *)

Prog

(PARI) is(n)=ispseudoprime(255*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A132527 A182327 A364270 * A041397 A042811 A261045

Adjacent sequences: A032501 A032502 A032503 * A032505 A032506 A032507

Keyword

nonn,hard,changed

Author

N. J. A. Sloane.

Extensions

a(46)-a(63) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 20 2018

Status

approved