A050895 Numbers k such that 273*2^k-1 is prime.

2, 6, 10, 15, 22, 26, 31, 42, 47, 98, 107, 123, 126, 175, 178, 203, 223, 230, 239, 279, 371, 402, 519, 607, 755, 830, 871, 927, 980, 1527, 1770, 2007, 2218, 2247, 2250, 3982, 4367, 4510, 9716, 13018, 20906, 26340, 40186, 63332, 84599, 119743, 156155, 206118, 238687

Offset

1,1

Links

Table of n, a(n) for n=1..49.

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[273*2^# - 1] & ] (* Robert Price, Dec 30 2018 *)

Prog

(PARI) is(n)=ispseudoprime(273*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A331250 A186783 A133931 * A184426 A293408 A357387

Adjacent sequences: A050892 A050893 A050894 * A050896 A050897 A050898

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(48)-a(49) from the Wilfrid Keller link by Robert Price, Dec 30 2018

Status

approved