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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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS 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 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 A039504 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

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Last modified December 1 23:44 EST 2022. Contains 358485 sequences. (Running on oeis4.)