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 A007670 Numbers n such that 2^n - 2^((n + 1)/2) + 1 is prime. (Formerly M2703) 8
 3, 7, 47, 73, 79, 113, 151, 167, 239, 241, 353, 367, 457, 1367, 3041, 27529, 49207, 160423, 364289, 991961, 1203793, 1667321, 4792057 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS If A007670 is a proper subset of A057429, then 364289 & 991961 are the next two terms. REFERENCES J. Brillhart et al., Factorizations of b^n +- 1. Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 2nd edition, 1985; and later supplements. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS J. Brillhart, Concerning the number 2^(2p)+1, p prime, Math. Comp. 16 (80) (1962) 424-430. J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002. S. S. Wagstaff, Jr., The Cunningham Project PROG (PARI) is(n)=isprime(2^n-2^((n+1)/2)+1) \\ Charles R Greathouse IV, Feb 17 2017 CROSSREFS Cf. A006598. Sequence in context: A231893 A132565 A129518 * A263806 A074714 A064457 Adjacent sequences:  A007667 A007668 A007669 * A007671 A007672 A007673 KEYWORD nonn,hard,more AUTHOR EXTENSIONS a(16)-a(18) from Robert G. Wilson v, Sep 07 2000 a(19)-a(23) from Serge Batalov, Jun 16 2020 STATUS approved

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Last modified September 21 13:20 EDT 2020. Contains 337272 sequences. (Running on oeis4.)