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 A086258 a(n) is the smallest k such that 2^k+1 has n primitive prime factors. 1
 0, 14, 26, 46, 83, 118, 309, 194, 414, 538, 786, 958 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A prime factor of 2^n+1 is called primitive if it does not divide 2^r+1 for any r 666. - David Wasserman, Feb 25 2005 REFERENCES J. Brillhart et al., Factorizations of b^n +- 1. Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002. LINKS J. Brillhart et al., Factorizations of b^n +- 1 Available on-line EXAMPLE a(2) = 14 because 2^14+1 = 5*29*113 and 29 and 113 do not divide 2^r+1 for r < 14. CROSSREFS Cf. A086252, A086257. Sequence in context: A242395 A112772 A155505 * A063799 A086451 A190991 Adjacent sequences:  A086255 A086256 A086257 * A086259 A086260 A086261 KEYWORD nonn,hard,more AUTHOR T. D. Noe, Jul 14 2003 EXTENSIONS More terms from David Wasserman, Feb 25 2005 a(11) from D. S. McNeil, Dec 19 2010 a(12) from Amiram Eldar, Oct 12 2019 STATUS approved

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Last modified August 18 10:34 EDT 2022. Contains 356212 sequences. (Running on oeis4.)