A050867 Numbers k such that 231*2^k-1 is prime.

1, 3, 6, 7, 21, 29, 46, 49, 54, 57, 73, 90, 118, 169, 207, 267, 287, 333, 354, 366, 370, 463, 493, 497, 507, 655, 729, 735, 757, 1054, 1377, 1770, 2098, 2886, 3225, 3611, 3625, 3657, 4849, 5706, 5749, 5771, 7110, 8395, 12150, 15658, 16182, 16693, 17363

Offset

1,2

Links

Robert Price, Table of n, a(n) for n = 1..63

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

Kosmaj, Riesel list 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[231*2^# - 1] & ] (* Robert Price, Dec 29 2018 *)

Prog

(PARI) is(n)=ispseudoprime(231*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A364007 A106357 A088101 * A019248 A284042 A288295

Adjacent sequences: A050864 A050865 A050866 * A050868 A050869 A050870

Keyword

hard,nonn

Author

N. J. A. Sloane, Dec 29 1999

Extensions

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008

a(50)-a(63) from the Wilfrid Keller link by Robert Price, Dec 29 2018

Status

approved