A050854 Numbers n such that 205*2^n-1 is prime.

1, 9, 39, 45, 49, 67, 75, 99, 129, 159, 177, 445, 721, 771, 829, 849, 865, 1971, 3045, 8397, 9019, 10749, 21037, 30529, 38349, 46257, 53577, 64695, 77451, 128019, 420297, 462261

Offset

1,2

Links

Table of n, a(n) for n=1..32.

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(205*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A071238 A213583 A343521 * A053181 A348545 A346950

Adjacent sequences: A050851 A050852 A050853 * A050855 A050856 A050857

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