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A004064
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Numbers k such that (12^k - 1)/11 is prime.
(Formerly M0744)
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16
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2, 3, 5, 19, 97, 109, 317, 353, 701, 9739, 14951, 37573, 46889, 769543
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OFFSET
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1,1
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COMMENTS
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Also, numbers k such that 12^k-1 is a semiprime. - Sean A. Irvine, Oct 16 2023
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REFERENCES
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J. Brillhart et al., Factorizations of b^n +- 1. Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 2nd edition, 1985; and later supplements.
J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 109, p. 38, Ellipses, Paris 2008.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
Eric Weisstein's World of Mathematics, Repunit
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MATHEMATICA
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PROG
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CROSSREFS
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KEYWORD
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nonn,hard
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AUTHOR
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EXTENSIONS
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One more term from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
a(13)=46889, discovered Sep 10 2008 by Paul Bourdelais, corresponds to a probable prime based on trial factoring to 10^13 and Fermat base 2 primality test. - Paul Bourdelais, Sep 11 2008
a(14)=769543 corresponds to a probable prime discovered by Paul Bourdelais, Dec 05 2014
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STATUS
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approved
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