This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A114302 #15 Dec 20 2016 09:43:03
%S A114302 2,3,6,18,106,2102,456774,7108935325
%N A114302 Number of "sweet" Boolean functions of n variables.
%C A114302 A sweet Boolean function is a monotone function whose BDD (binary decision diagram) is the same as the ZDD (zero-suppressed decision diagram) for its prime implicants (aka minimal solutions).
%C A114302 Equivalently, this is the number of sweet antichains contained in {1,...,n}. (Also called sweet clutters.) A sweet antichain whose largest element is n is a family of subsets A \cup (n\cup B) where A and B are sweet antichains in {1,...n-1}, B is nonempty and every element of A properly contains some element of B.
%C A114302 The property of being "sweet" depends on the order of the variables - compare A114491.
%D A114302 Donald E. Knuth, The Art of Computer Programming, Vol. 4, fascicle 1, section 7.1.4, p. 117, Addison-Wesley, 2009.
%e A114302 All six of the antichains in {1,2} are sweet. They are emptyset, {emptyset}, {{1}}, {{2}}, {{1,2}} and {{1},{2}}.
%e A114302 Only 18 of the 20 antichains in {1,2,3} are sweet. The nonsweet ones are {{1,3},{2}} and {{1},{2,3}}. Because, in the latter case, A={1} and B={2}. However, {{1,2},{3}} is sweet because A={{1,2}} and B={emptyset}.
%e A114302 Some of the most interesting members of this apparently new family of Boolean functions are the connectedness functions, defined on the edges of any graph. The function f=[these arcs give a connected subgraph] is sweet, under any ordering of the arcs. Threshold functions [x_1+...+x_n >= k] are sweet too.
%e A114302 Also the conjunction of sweet functions on disjoint sets of variables is sweet.
%Y A114302 Cf. A114303, A114492, A114572.
%K A114302 nonn,more
%O A114302 0,1
%A A114302 _Don Knuth_, Aug 16 2008