A050550 - OEIS

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A050550

Numbers n such that 49*2^n-1 is prime.

0

1, 5, 7, 9, 13, 15, 29, 33, 39, 55, 81, 95, 205, 279, 581, 807, 813, 2551, 2565, 3183, 6661, 11989, 16911, 22605, 30799, 39969, 41167, 43421, 54559, 212745, 290631, 332231, 460989, 542945, 691469

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..35.

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(49*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Cf. A032374, 49*2^n+1 is prime.

Sequence in context: A302482 A284742 A111083 * A079523 A231271 A359198

Adjacent sequences: A050547 A050548 A050549 * A050551 A050552 A050553

KEYWORD

hard,nonn

AUTHOR

N. J. A. Sloane, Dec 29 1999

EXTENSIONS

More terms from Hugo Pfoertner, Oct 13 2004

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

STATUS

approved