A050860 - OEIS

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A050860

Numbers n such that 217*2^n-1 is prime.

0

1, 9, 21, 133, 233, 1393, 1453, 1769, 2041, 3985, 17501, 80341, 148089, 205525, 327829, 377581, 398605

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..17.

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(217*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Sequence in context: A222809 A230648 A177125 * A339724 A342409 A373747

Adjacent sequences: A050857 A050858 A050859 * A050861 A050862 A050863

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