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%I #13 Oct 12 2019 19:07:58
%S 0,14,26,46,83,118,309,194,414,538,786,958
%N a(n) is the smallest k such that 2^k+1 has n primitive prime factors.
%C A prime factor of 2^n+1 is called primitive if it does not divide 2^r+1 for any r<n. See A086257 for the number of primitive prime factors in 2^n+1. It is known that a(8) = 194.
%C Next term is > 666. - _David Wasserman_, Feb 25 2005
%D J. Brillhart et al., Factorizations of b^n +- 1. Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
%H J. Brillhart et al., Factorizations of b^n +- 1 <a href="http://dx.doi.org/10.1090/conm/022">Available on-line</a>
%e a(2) = 14 because 2^14+1 = 5*29*113 and 29 and 113 do not divide 2^r+1 for r < 14.
%Y Cf. A086252, A086257.
%K nonn,hard,more
%O 1,2
%A _T. D. Noe_, Jul 14 2003
%E More terms from _David Wasserman_, Feb 25 2005
%E a(11) from _D. S. McNeil_, Dec 19 2010
%E a(12) from _Amiram Eldar_, Oct 12 2019
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