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 A273945 Odd prime factors of generalized Fermat numbers of the form 3^(2^m) + 1 with m >= 0. 8

%I

%S 5,17,41,193,257,12289,59393,65537,275201,786433,790529,8972801,

%T 13631489,21523361,134382593,155189249,448524289,524455937,847036417,

%U 3221225473,12348030977,22320686081,77309411329,206158430209,4638564679681,6597069766657,12079910333441

%N Odd prime factors of generalized Fermat numbers of the form 3^(2^m) + 1 with m >= 0.

%C Odd primes p such that the multiplicative order of 3 (mod p) is a power of 2.

%H Arkadiusz Wesolowski, <a href="/A273945/b273945.txt">Table of n, a(n) for n = 1..35</a>

%H Anders Björn and Hans Riesel, <a href="http://dx.doi.org/10.1090/S0025-5718-98-00891-6">Factors of generalized Fermat numbers</a>, Math. Comp. 67 (1998), no. 221, pp. 441-446.

%H Anders Björn and Hans Riesel, <a href="http://dx.doi.org/10.1090/S0025-5718-05-01816-8">Table errata to “Factors of generalized Fermat numbers”</a>, Math. Comp. 74 (2005), no. 252, p. 2099.

%H Anders Björn and Hans Riesel, <a href="http://dx.doi.org/10.1090/S0025-5718-10-02371-9">Table errata 2 to "Factors of generalized Fermat numbers"</a>, Math. Comp. 80 (2011), pp. 1865-1866.

%H C. K. Caldwell, Top Twenty page, <a href="http://primes.utm.edu/top20/page.php?id=28">Generalized Fermat Divisors (base=3)</a>

%H Harvey Dubner and Wilfrid Keller, <a href="http://dx.doi.org/10.1090/S0025-5718-1995-1270618-1">Factors of Generalized Fermat Numbers</a>, Math. Comp. 64 (1995), no. 209, pp. 397-405.

%H OEIS Wiki, <a href="/wiki/Generalized_Fermat_numbers">Generalized Fermat numbers</a>

%H Hans Riesel, <a href="http://dx.doi.org/10.1007/BF01946818">Common prime factors of the numbers A_n=a^(2^n)+1</a>, BIT 9 (1969), pp. 264-269.

%t Select[Prime@Range[2, 10^5], IntegerQ@Log[2, MultiplicativeOrder[3, #]] &]

%Y Cf. A023394, A059919, A072982, A268657, A268661, A273946 (base 5), A273947 (base 6), A273948 (base 7), A273949 (base 11), A273950 (base 12).

%K nonn

%O 1,1

%A _Arkadiusz Wesolowski_, Jun 05 2016

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Last modified February 22 12:33 EST 2020. Contains 332136 sequences. (Running on oeis4.)