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%I #5 Oct 17 2023 08:34:58
%S 2,4,5,11,16,32,109,128,193
%N Numbers k such that 12^k + 1 is a semiprime.
%e 11 is in this sequence because 12^11+1 = 13*57154490053 is a semiprime.
%Y Cf. A178248, A001358, A004064, A366582.
%K nonn,more
%O 1,1
%A _Sean A. Irvine_, Oct 16 2023