cp's OEIS Frontend

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

%I A273945 #19 Apr 03 2023 10:36:13
%S A273945 5,17,41,193,257,12289,59393,65537,275201,786433,790529,8972801,
%T A273945 13631489,21523361,134382593,155189249,448524289,524455937,847036417,
%U A273945 3221225473,12348030977,22320686081,77309411329,206158430209,4638564679681,6597069766657,12079910333441
%N A273945 Odd prime factors of generalized Fermat numbers of the form 3^(2^m) + 1 with m >= 0.
%C A273945 Odd primes p such that the multiplicative order of 3 (mod p) is a power of 2.
%H A273945 Arkadiusz Wesolowski, <a href="/A273945/b273945.txt">Table of n, a(n) for n = 1..35</a>
%H A273945 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 A273945 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 A273945 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 A273945 C. K. Caldwell, Top Twenty page, <a href="https://t5k.org/top20/page.php?id=28">Generalized Fermat Divisors (base=3)</a>
%H A273945 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 A273945 OEIS Wiki, <a href="/wiki/Generalized_Fermat_numbers">Generalized Fermat numbers</a>
%H A273945 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 A273945 Select[Prime@Range[2, 10^5], IntegerQ@Log[2, MultiplicativeOrder[3, #]] &]
%Y A273945 Cf. A023394, A059919, A072982, A268657, A268661, A273946 (base 5), A273947 (base 6), A273948 (base 7), A273949 (base 11), A273950 (base 12).
%K A273945 nonn
%O A273945 1,1
%A A273945 _Arkadiusz Wesolowski_, Jun 05 2016