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 A319621 #8 Oct 26 2018 12:50:18
%S A319621 1,1,1,2,7,73
%N A319621 Number of non-isomorphic connected antichain covers of n vertices by distinct sets whose dual is also an antichain of (not necessarily distinct) sets.
%C A319621 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}}.
%e A319621 Non-isomorphic representatives of the a(1) = 1 through a(4) = 7 antichain covers:
%e A319621 {{1}} {{1,2}} {{1,2,3}} {{1,2,3,4}}
%e A319621 {{1,2},{1,3},{2,3}} {{1,2},{1,3,4},{2,3,4}}
%e A319621 {{1,2},{1,3},{2,4},{3,4}}
%e A319621 {{1,2},{1,3},{1,4},{2,3,4}}
%e A319621 {{1,3},{1,4},{2,3},{2,4},{3,4}}
%e A319621 {{1,2,3},{1,2,4},{1,3,4},{2,3,4}}
%e A319621 {{1,2},{1,3},{1,4},{2,3},{2,4},{3,4}}
%Y A319621 Cf. A006126, A007716, A007718, A049311, A056156, A059201, A316980, A316983, A318099, A319557, A319565, A319616-A319646, A300913.
%K A319621 nonn,more
%O A319621 0,4
%A A319621 _Gus Wiseman_, Sep 25 2018