A050553 Numbers n such that 55*2^n-1 is prime.

1, 3, 5, 7, 15, 33, 41, 57, 69, 75, 77, 131, 133, 153, 247, 305, 351, 409, 471, 1251, 1259, 2253, 2411, 2425, 2699, 3221, 4099, 4173, 4291, 4905, 5349, 6723, 7143, 7505, 10539, 10557, 12099, 17373, 23721, 27895, 33801, 35519, 45927, 63589, 73287, 96933, 106659, 218043, 253047, 397941, 651015

Offset: 1

Author

N. J. A. Sloane, Dec 29 1999

Keywords

• hard
• nonn

Links

• 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.

Crossrefs

Cf. A057813.

Programs

PARI

is(n)=ispseudoprime(55*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

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