The OEIS is supported by the many generous donors to the OEIS Foundation.
%I #5 Aug 08 2015 23:58:33
%S 2,3,6,17,69,407,3808,75165,10607541
%N Number of "ultrasweet" Boolean functions of n variables.
%C A Boolean function is ultrasweet if it is sweet (see A114302) under all permutations of the variables.
%C Two students, Shaddin Dughmi and Ian Post, have identified these functions as precisely the monotone Boolean functions whose prime implicants are the bases of a matroid, together with the constant function 0. This explains why a(n) = A058673(n) + 1.
%e For all n>1, a function like "x2" is counted in the present sequence but not in A114572.
%Y Cf. A114302, A114303, A114572, A058673.
%K nonn
%O 0,1
%A _Don Knuth_, Aug 17 2008, Oct 14 2008