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%I #54 Jan 16 2023 08:07:49
%S 67,9431,461081,2543551
%N Numbers k such that 9*2^k + 1 is a prime factor of a Fermat number 2^(2^m) + 1 for some m.
%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 Subsequence of A002256.
%Y Cf. A000215, A050528, A057778, A201364, A204620, A226366, A280003.
%K nonn,hard,more
%O 1,1
%A _Arkadiusz Wesolowski_, Feb 21 2017
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