A032472 Numbers k such that 191*2^k+1 is prime.

1, 5, 15, 19, 41, 59, 89, 149, 167, 181, 201, 295, 475, 481, 857, 1249, 1409, 1715, 1995, 8291, 11031, 26219, 38029, 39155, 61747, 73855, 168707, 180559, 266997, 366215, 449381, 552085, 585377, 903061, 1099867, 1487775, 1496507, 1567005, 1766221, 1916611

Offset

1,2

Comments

The subsequence of prime values starts 5, 19, 41, 59, 89, 149, 167, 181, 857, 1249, 1409, 8291, 449381, 1099867, 1496507, 1916611, ... - Muniru A Asiru, Apr 20 2019

Links

Jeppe Stig Nielsen, Table of n, a(n) for n = 1..41

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

Maple

select(k->isprime(191*2^k+1), [$0..1000]); # Muniru A Asiru, Dec 18 2018

Mathematica

Select[Range[1000], PrimeQ[191*2^# + 1] & ] (* Robert Price, Dec 18 2018 *)

Prog

(PARI) is(n)=ispseudoprime(191*2^n+1) \\ Charles R Greathouse IV, Jun 07 2017

Crossrefs

Sequence in context: A102180 A365910 A045520 * A290551 A045176 A273908

Adjacent sequences: A032469 A032470 A032471 * A032473 A032474 A032475

Keyword

nonn,hard

Author

N. J. A. Sloane

Extensions

a(27)-a(40) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 18 2018

Status

approved