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%I #7 Mar 30 2012 18:40:59
%S 1,5,188,3684030417
%N Number of nonisomorphic semigroups of order 2^n.
%C This is to A000679 as semigroups are to groups.
%F a(n) = A027851(A000079(n)).
%e a(3) = 3684030417 because there are 3684030417 nonisomorphic semigroups of order 2^3 = 8.
%Y Cf. A000079, A000679 Number of groups of order 2^n, A027851 Number of nonisomorphic semigroups of order n.
%K nonn,hard
%O 0,2
%A _Jonathan Vos Post_, Mar 08 2012