A050616 Numbers k such that 149*2^k-1 is prime.

4, 16, 48, 60, 240, 256, 304, 2644, 3720, 25132, 39472, 212460, 592968

Offset

1,1

Comments

All terms appear to be multiples of four. - Robert Price, Dec 23 2018

Links

Table of n, a(n) for n=1..13.

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

Kosmaj, Riesel list k<300.

Mathematica

Select[Range[1000], PrimeQ[149*2^# - 1] & ] (* Robert Price, Dec 23 2018 *)

Prog

(PARI) is(n)=ispseudoprime(149*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A244252 A369401 A308592 * A297160 A006009 A261977

Adjacent sequences: A050613 A050614 A050615 * A050617 A050618 A050619

Keyword

hard,nonn,more

Author

N. J. A. Sloane, Dec 29 1999

Extensions

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

Status

approved