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A268657
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Numbers k such that 3*2^k + 1 is a prime factor of a generalized Fermat number 3^(2^m) + 1 for some m.
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11
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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
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OFFSET
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1,1
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REFERENCES
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Wilfrid Keller, private communication, 2008.
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LINKS
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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
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PROG
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(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
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CROSSREFS
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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
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KEYWORD
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nonn
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AUTHOR
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Arkadiusz Wesolowski, Feb 10 2016
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STATUS
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approved
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