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 A050587 Numbers n such that 123*2^n-1 is prime. 0
 2, 3, 11, 15, 23, 24, 27, 35, 71, 84, 108, 122, 123, 138, 236, 242, 290, 392, 500, 611, 747, 771, 1106, 1490, 3560, 5111, 6066, 8660, 8927, 19451, 19730, 28316, 30471, 49515, 93762, 117083, 168435, 206663, 249242, 255402, 261530, 355727, 389052, 516456, 518540, 521031 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 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(123*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017 CROSSREFS Sequence in context: A036972 A041637 A042235 * A293026 A178430 A295128 Adjacent sequences:  A050584 A050585 A050586 * A050588 A050589 A050590 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 October 20 20:24 EDT 2019. Contains 328273 sequences. (Running on oeis4.)