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 A242797 Numbers n such that (45^n - 1)/44 is prime. 5
 19, 53, 167, 3319, 11257, 34351 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(7) > 10^5. Numbers corresponding to a(4)-a(6) are probable primes. All terms are prime. LINKS Harvey Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930. Henri Lifchitz, Mersenne and Fermat primes field MAPLE A242797:=n->`if`(isprime((45^n - 1)/44), n, NULL); seq(A242797(n), n=1..100000); # Wesley Ivan Hurt, Apr 12 2014 MATHEMATICA Select[Prime[Range[100000]], PrimeQ[(45^# - 1)/44] &] PROG (PARI) is(n)=ispseudoprime((45^n-1)/44) \\ Charles R Greathouse IV, Feb 20 2017 CROSSREFS Cf. A028491, A004061, A004062, A004063, A004023, A005808, A004064, A016054, A006032, A006033, A006034, A006035, A127995, A127996, A127997, A127998, A127999, A098438, A128002, A128003, A128004, A128005, A240765. Sequence in context: A024848 A240136 A072581 * A142072 A221594 A288144 Adjacent sequences:  A242794 A242795 A242796 * A242798 A242799 A242800 KEYWORD hard,more,nonn AUTHOR Robert Price, May 22 2014 STATUS approved

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Last modified December 12 10:19 EST 2019. Contains 329953 sequences. (Running on oeis4.)