A032498 Numbers k such that 243*2^k+1 is prime.

1, 4, 12, 13, 18, 24, 49, 64, 78, 144, 148, 204, 258, 453, 796, 1309, 1612, 1812, 3873, 4348, 6354, 7996, 8536, 10128, 11289, 29544, 32773, 123114, 130998, 153417, 168093, 241602, 487938, 495732, 555984, 997537, 1177629, 1284429, 1516368, 1742689, 2685873

Offset

1,2

Links

Jeppe Stig Nielsen, 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[243*2^# + 1] & ] (* Robert Price, Dec 20 2018 *)

Prog

(PARI) is(n)=ispseudoprime(243*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A103053 A087760 A237279 * A144613 A031330 A052339

Adjacent sequences: A032495 A032496 A032497 * A032499 A032500 A032501

Keyword

nonn,hard

Author

N. J. A. Sloane.

Extensions

a(31)-a(40) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 20 2018

a(41) (and b-file) from Jeppe Stig Nielsen, Jan 18 2020

Status

approved