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 A050560 Numbers n such that 69*2^n-1 is prime. 0
 1, 4, 5, 7, 9, 11, 13, 17, 19, 23, 29, 37, 49, 61, 79, 99, 121, 133, 141, 164, 173, 181, 185, 193, 233, 299, 313, 351, 377, 540, 569, 909, 1057, 1081, 1189, 1679, 2043, 2641, 3471, 3533, 3943, 5607, 9681, 12879, 14513, 15300, 21573, 30895, 32163, 39983, 47167, 47657, 49325, 51881, 64801, 65385, 65723, 66017, 69020, 74111, 76803, 79956, 83761, 84437, 100916, 110617, 165841, 195515, 234305, 234916, 236989, 239019, 352196, 362787, 464843, 580596, 613781, 820237, 831617, 867653, 978209 (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(69*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017 CROSSREFS Sequence in context: A223134 A339690 A267087 * A204664 A283554 A035243 Adjacent sequences:  A050557 A050558 A050559 * A050561 A050562 A050563 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

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Last modified July 30 22:16 EDT 2021. Contains 346365 sequences. (Running on oeis4.)