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%I #4 Mar 02 2017 02:37:59
%S 3,5,6,10
%N Positive integers n such that none of the primes of the form k*2^n + 1 (with k odd) divide any Fermat number F(m) = 2^(2^m) + 1, m >= 0.
%C Conjecture: sequence is infinite.
%C a(5) >= 18.
%H Proth Search Page, <a href="http://www.prothsearch.com/fermat.html">Prime factors of Fermat numbers</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/FermatNumber.html">Fermat Number</a>
%Y Cf. A019434, A023394, A228845, A228846, A229857, A231203.
%K nonn,hard,more
%O 1,1
%A _Arkadiusz Wesolowski_, Feb 27 2017
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