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 A006032 Numbers n such that (14^n - 1)/13 is prime. (Formerly M2670) 12
 3, 7, 19, 31, 41, 2687, 19697, 59693, 67421, 441697 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Paul Bourdelais, A Generalized Repunit Conjecture H. Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930. H. Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930. [Annotated scanned copy] H. Lifchitz, Mersenne and Fermat primes field MATHEMATICA lst={}; Do[If[PrimeQ[(14^n-1)/13], Print[n]; AppendTo[lst, n]], {n, 10^5}]; lst (* Vladimir Joseph Stephan Orlovsky, Aug 21 2008 *) PROG (PARI) is(n)=isprime((14^n - 1)/13) \\ Charles R Greathouse IV, Apr 29 2015 CROSSREFS Sequence in context: A056725 A091738 A136054 * A240072 A066148 A093932 Adjacent sequences:  A006029 A006030 A006031 * A006033 A006034 A006035 KEYWORD hard,nonn,more AUTHOR EXTENSIONS One more term from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008 a(8) and a(9) correspond to probable primes discovered by Paul Bourdelais, Mar 01 2010 a(10) corresponds to a probable prime discovered by Paul Bourdelais, Dec 08 2014 STATUS approved

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Last modified December 7 20:33 EST 2019. Contains 329849 sequences. (Running on oeis4.)