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 A319631 #6 Oct 26 2018 12:50:18
%S A319631 1,1,2,3,5,5,13,11,25,31,54
%N A319631 Number of non-isomorphic weight-n antichains of multisets whose dual is a chain of distinct multisets.
%C A319631 The dual of a multiset partition has, for each vertex, one block consisting of the indices (or positions) of the blocks containing that vertex, counted with multiplicity. For example, the dual of {{1,2},{2,2}} is {{1},{1,2,2}}.
%C A319631 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 A319631 Non-isomorphic representatives of the a(1) = 1 through a(5) = 5 antichains:
%e A319631 1: {{1}}
%e A319631 2: {{1,1}}
%e A319631 {{1},{1}}
%e A319631 3: {{1,1,1}}
%e A319631 {{1,2,2}}
%e A319631 {{1},{1},{1}}
%e A319631 4: {{1,1,1,1}}
%e A319631 {{1,2,2,2}}
%e A319631 {{1,1},{1,1}}
%e A319631 {{1,2},{2,2}}
%e A319631 {{1},{1},{1},{1}}
%e A319631 5: {{1,1,1,1,1}}
%e A319631 {{1,1,2,2,2}}
%e A319631 {{1,2,2,2,2}}
%e A319631 {{1,2},{2,2,2}}
%e A319631 {{1},{1},{1},{1},{1}}
%Y A319631 Cf. A000219, A006126, A007716, A059201, A293606, A316980, A316983, A318099, A319558, A319616-A319646, A300913.
%K A319631 nonn,more
%O A319631 0,3
%A A319631 _Gus Wiseman_, Sep 25 2018