A032412 Numbers k such that 125*2^k+1 is prime.

1, 5, 7, 17, 25, 35, 67, 281, 331, 491, 581, 941, 1205, 1279, 1411, 1631, 1895, 2735, 3475, 13955, 50491, 68819, 423155, 432719, 507637, 701981, 924085, 1107425, 2071555, 2369461

Offset

1,2

Links

Table of n, a(n) for n=1..30.

Ray Ballinger, Proth Search Page

Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for k < 300

Y. Gallot, Proth.exe: Windows Program for Finding Large Primes

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[125*2^# + 1] & ] (* Robert Price, Dec 17 2018 *)

Prog

(PARI) is(n)=ispseudoprime(125*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A025085 A175238 A240030 * A114970 A048710 A126142

Adjacent sequences: A032409 A032410 A032411 * A032413 A032414 A032415

Keyword

nonn,more

Author

James R. Buddenhagen

Extensions

a(23)-a(29) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 17 2018

a(30) from Jeppe Stig Nielsen, Apr 04 2020

Status

approved