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%I #13 Sep 28 2015 21:41:41
%S 29,11,4679,131063,123817,318949,209510599,49977801259,2199023255531,
%T 9334079,7250118529,2305843009213693921,17457916757373919459,
%U 27748320404471,717308900550128276543,2028240960365167042394725128581,221537999297485978817301176713390723
%N Largest prime factor of the semiprime 2^A165767(n)-A165767(n).
%C A165768(n)=2 <=> A165767(n)=2k for some k <=> a(n)=4^k/2-k is prime. This is the case for k=3,9,21,31,1125,...
%H Max Alekseyev, <a href="/A165769/b165769.txt">Table of n, a(n) for n = 1..39</a>
%F a(n)=(2^A165767(n)-A165767(n))/A165768(n).
%e 46235097144973199564251065756966919577339221 is in this sequence because it is the largest prime factor of the semiprime 2^199-199.
%K nonn
%O 1,1
%A _M. F. Hasler_, Oct 08 2009
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