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 A268657 Numbers k such that 3*2^k + 1 is a prime factor of a generalized Fermat number 3^(2^m) + 1 for some m. 11
 6, 12, 18, 30, 36, 41, 66, 189, 201, 209, 276, 408, 438, 534, 2208, 3168, 3189, 3912, 34350, 42294, 44685, 48150, 54792, 55182, 59973, 80190, 157169, 213321, 303093, 382449, 709968, 801978, 916773, 1832496, 2145353, 2291610, 2478785, 5082306, 7033641, 10829346 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 REFERENCES Wilfrid Keller, private communication, 2008. LINKS Jeppe Stig Nielsen, Table of n, a(n) for n = 1..41 Anders Björn and Hans Riesel, Factors of generalized Fermat numbers, Math. Comp. 67 (1998), no. 221, pp. 441-446. Anders Björn and Hans Riesel, Table errata to “Factors of generalized Fermat numbers”, Math. Comp. 74 (2005), no. 252, p. 2099. Anders Björn and Hans Riesel, Table errata 2 to "Factors of generalized Fermat numbers", Math. Comp. 80 (2011), pp. 1865-1866. C. K. Caldwell, Top Twenty page, Generalized Fermat Divisors (base=3) OEIS Wiki, Generalized Fermat numbers PROG (PARI) for(k=1, +oo, p=3*2^k+1; if(ispseudoprime(p), t=znorder(Mod(3, p)); bitand(t, t-1)==0&&print1(k, ", "))) \\ Jeppe Stig Nielsen, Oct 30 2020 CROSSREFS Cf. A059919, A268658, A204620, A268659, A268660, A268661, A268662, A268663, A226366, A268664. Subsequence of A002253. Sequence in context: A057826 A334543 A330853 * A232742 A268928 A162864 Adjacent sequences:  A268654 A268655 A268656 * A268658 A268659 A268660 KEYWORD nonn AUTHOR Arkadiusz Wesolowski, Feb 10 2016 STATUS approved

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Last modified January 20 17:22 EST 2021. Contains 340303 sequences. (Running on oeis4.)