A050855 - OEIS

A050855

Numbers n such that 207*2^n-1 is prime.

2, 9, 12, 17, 20, 21, 50, 53, 132, 168, 341, 360, 381, 501, 1065, 1169, 1545, 2109, 2520, 2661, 3149, 4077, 11252, 21588, 21692, 39509, 52685, 67196, 87708, 232436, 372312, 417818, 481385, 507833

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OFFSET

1,1

COMMENTS

Also in the sequence: 643478 - Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008

LINKS

Table of n, a(n) for n=1..34.

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(207*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Sequence in context: A124742 A152003 A251428 * A031070 A350630 A225547

Adjacent sequences: A050852 A050853 A050854 * A050856 A050857 A050858

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