A032493 Numbers k such that 233*2^k+1 is prime.

1, 5, 9, 13, 17, 25, 33, 53, 57, 77, 521, 593, 609, 845, 917, 985, 1321, 1801, 3565, 4953, 5137, 13193, 14173, 15517, 15629, 21853, 22009, 24625, 40041, 47797, 50257, 52433, 114881, 174785, 294485, 331321, 355945, 517373, 768241, 1649741, 1662513, 2022801

Offset

1,2

Links

Table of n, a(n) for n=1..42.

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[233*2^# + 1] & ] (* Robert Price, Dec 19 2018 *)

Prog

(PARI) is(n)=ispseudoprime(233*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A057653 A085759 A314700 * A362256 A349538 A334524

Adjacent sequences: A032490 A032491 A032492 * A032494 A032495 A032496

Keyword

nonn,hard

Author

N. J. A. Sloane.

Extensions

a(34)-a(41) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 19 2018

a(42) from Jeppe Stig Nielsen, May 31 2020

Status

approved