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A002589
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Largest primitive factor of 2^(2n+1) + 1.
(Formerly M2234 N0886)
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4
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3, 1, 11, 43, 19, 683, 2731, 331, 43691, 174763, 5419, 2796203, 4051, 87211, 3033169, 715827883, 20857, 86171, 25781083, 22366891, 8831418697, 2932031007403, 18837001, 165768537521, 4363953127297, 6529, 28059810762433, 48912491, 160465489
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OFFSET
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0,1
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COMMENTS
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Also excludes intrinsic factors which is why a(1)=1 rather than 3. - Sean A. Irvine, Apr 20 2014
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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.
M. Kraitchik, Recherches sur la Théorie des Nombres. Gauthiers-Villars, Paris, Vol. 1, 1924, Vol. 2, 1929, see Vol. 2, p. 85.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
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.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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a(473)-a(560) from Max Alekseyev, Feb 09 2020, Sep 10 2020, Dec 21 2022, Jul 25 2023
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STATUS
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approved
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