A032465 Numbers k such that 177*2^k+1 is prime.

2, 4, 6, 12, 16, 20, 23, 32, 38, 48, 54, 60, 100, 116, 118, 119, 140, 150, 163, 170, 190, 244, 271, 294, 299, 320, 334, 414, 439, 442, 468, 724, 794, 842, 864, 1032, 1750, 2050, 3980, 4010, 4756, 5096, 5963, 5966, 6836, 14160, 16748, 16844, 19814, 25398

Offset

1,1

Comments

The subsequence of prime values starts 2, 23, 163, 271, 439, 798443, ... - Muniru A Asiru, Apr 29 2019

Links

Jeppe Stig Nielsen, Table of n, a(n) for n = 1..74 (terms n = 1..73 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

Maple

select(k->isprime(177*2^k+1), [$0..1000]); # Muniru A Asiru, Dec 18 2018

Mathematica

Select[Range[1000], PrimeQ[177*2^# + 1] & ] (* Robert Price, Dec 18 2018 *)

Prog

(PARI) is(n)=ispseudoprime(177*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A019280 A090748 A188047 * A089395 A089699 A089696

Adjacent sequences: A032462 A032463 A032464 * A032466 A032467 A032468

Keyword

nonn,hard

Author

N. J. A. Sloane.

Extensions

a(51)-a(73) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 18 2018

Status

approved