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 A319619 #7 Oct 26 2018 12:50:18
%S A319619 1,1,3,3,6,4,15,13,48,96,280
%N A319619 Number of non-isomorphic connected weight-n antichains of multisets whose dual is also an antichain of multisets.
%C A319619 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 A319619 The weight of a multiset partition is the sum of sizes of its parts. Weight is generally not the same as number of vertices.
%F A319619 Euler transform is A318099.
%e A319619 Non-isomorphic representatives of the a(1) = 1 through a(5) = 4 antichains:
%e A319619 1: {{1}}
%e A319619 2: {{1,1}}
%e A319619 {{1,2}}
%e A319619 {{1},{1}}
%e A319619 3: {{1,1,1}}
%e A319619 {{1,2,3}}
%e A319619 {{1},{1},{1}}
%e A319619 4: {{1,1,1,1}}
%e A319619 {{1,1,2,2}}
%e A319619 {{1,2,3,4}}
%e A319619 {{1,1},{1,1}}
%e A319619 {{1,2},{1,2}}
%e A319619 {{1},{1},{1},{1}}
%e A319619 5: {{1,1,1,1,1}}
%e A319619 {{1,2,3,4,5}}
%e A319619 {{1,1},{1,2,2}}
%e A319619 {{1},{1},{1},{1},{1}}
%Y A319619 Cf. A006126, A007716, A007718, A056156, A059201, A316980, A316983, A318099, A319557, A319558, A319565, A319616-A319646, A300913.
%K A319619 nonn,more
%O A319619 0,3
%A A319619 _Gus Wiseman_, Sep 25 2018