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 A057177 Numbers n such that (11^n + 1)/12 is a prime. 13
 5, 7, 179, 229, 439, 557, 6113, 223999, 327001 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Paul Bourdelais, A Generalized Repunit Conjecture J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002. H. Dubner and T. Granlund, Primes of the Form (b^n+1)/(b+1), J. Integer Sequences, 3 (2000), #P00.2.7. H. Lifchitz, Mersenne and Fermat primes field Eric Weisstein's World of Mathematics, Repunit MATHEMATICA lst={}; Do[p=(11^n+1)/12; If[PrimeQ[p], AppendTo[lst, n]], {n, 7!}]; lst (* Vladimir Joseph Stephan Orlovsky, Sep 29 2008 *) CROSSREFS Sequence in context: A083842 A164372 A123536 * A211769 A265031 A229030 Adjacent sequences:  A057174 A057175 A057176 * A057178 A057179 A057180 KEYWORD nonn AUTHOR N. J. A. Sloane, Sep 15 2000 EXTENSIONS a(8) corresponds to a probable prime discovered by Paul Bourdelais, Feb 12 2010 a(9) corresponds to a probable prime discovered by Paul Bourdelais, Sep 30 2013 STATUS approved

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