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 A321678 #5 Nov 18 2018 15:06:13
%S A321678 1,0,1,1,3,3,11,13,39,67,174
%N A321678 Number of non-isomorphic weight-n strict antichains of sets with no singletons.
%C A321678 The weight of a multiset partition is the sum of sizes of its parts. Weight is generally not the same as number of vertices.
%e A321678 Non-isomorphic representatives of the a(2) = 1 through a(6) = 11 antichains:
%e A321678 {{1,2}} {{1,2,3}} {{1,2,3,4}} {{1,2,3,4,5}} {{1,2,3,4,5,6}}
%e A321678 {{1,2},{3,4}} {{1,2},{3,4,5}} {{1,2},{3,4,5,6}}
%e A321678 {{1,3},{2,3}} {{1,4},{2,3,4}} {{1,2,3},{4,5,6}}
%e A321678 {{1,2,5},{3,4,5}}
%e A321678 {{1,3,4},{2,3,4}}
%e A321678 {{1,5},{2,3,4,5}}
%e A321678 {{1,2},{1,3},{2,3}}
%e A321678 {{1,2},{3,4},{5,6}}
%e A321678 {{1,2},{3,5},{4,5}}
%e A321678 {{1,3},{2,4},{3,4}}
%e A321678 {{1,4},{2,4},{3,4}}
%Y A321678 Cf. A006126, A049311, A096827, A285572, A293993, A293994, A318099, A319719, A319721, A320799, A321679.
%K A321678 nonn,more
%O A321678 0,5
%A A321678 _Gus Wiseman_, Nov 16 2018