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 A273945 Odd prime factors of generalized Fermat numbers of the form 3^(2^m) + 1 with m >= 0. 8
 5, 17, 41, 193, 257, 12289, 59393, 65537, 275201, 786433, 790529, 8972801, 13631489, 21523361, 134382593, 155189249, 448524289, 524455937, 847036417, 3221225473, 12348030977, 22320686081, 77309411329, 206158430209, 4638564679681, 6597069766657, 12079910333441 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Odd primes p such that the multiplicative order of 3 (mod p) is a power of 2. LINKS Arkadiusz Wesolowski, Table of n, a(n) for n = 1..35 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) Harvey Dubner and Wilfrid Keller, Factors of Generalized Fermat Numbers, Math. Comp. 64 (1995), no. 209, pp. 397-405. OEIS Wiki, Generalized Fermat numbers Hans Riesel, Common prime factors of the numbers A_n=a^(2^n)+1, BIT 9 (1969), pp. 264-269. MATHEMATICA Select[Prime@Range[2, 10^5], IntegerQ@Log[2, MultiplicativeOrder[3, #]] &] CROSSREFS Cf. A023394, A059919, A072982, A268657, A268661, A273946 (base 5), A273947 (base 6), A273948 (base 7), A273949 (base 11), A273950 (base 12). Sequence in context: A130739 A147412 A273116 * A111268 A106973 A102264 Adjacent sequences:  A273942 A273943 A273944 * A273946 A273947 A273948 KEYWORD nonn AUTHOR Arkadiusz Wesolowski, Jun 05 2016 STATUS approved

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Last modified September 23 15:06 EDT 2020. Contains 337310 sequences. (Running on oeis4.)