A050889 Numbers n such that 261*2^n-1 is prime.

1, 3, 6, 9, 21, 34, 43, 49, 114, 115, 178, 322, 411, 438, 454, 589, 598, 754, 801, 1173, 1546, 1699, 2155, 2994, 4038, 5439, 6442, 10699, 12274, 13314, 13911, 19309, 28675, 29658, 31173, 33606, 65763, 90861, 116706, 185823, 618918, 660709, 802123

Offset

1,2

Links

Table of n, a(n) for n=1..43.

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.

Prog

(PARI) is(n)=ispseudoprime(261*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A116614 A089001 A215666 * A327140 A329863 A026095

Adjacent sequences: A050886 A050887 A050888 * A050890 A050891 A050892

Keyword

hard,nonn

Author

N. J. A. Sloane, Dec 29 1999

Extensions

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

Status

approved