cp's OEIS Frontend

A319633 Number of antichain covers of n vertices by distinct sets whose dual is also an antichain of (not necessarily distinct) sets.

%I A319633 #6 Oct 26 2018 12:50:18
%S A319633 1,1,2,6,40,2309
%N A319633 Number of antichain covers of n vertices by distinct sets whose dual is also an antichain of (not necessarily distinct) sets.
%C A319633 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 A319633 The a(3) = 6 antichain covers:
%e A319633    {{1,2,3}}
%e A319633    {{3},{1,2}}
%e A319633    {{2},{1,3}}
%e A319633    {{1},{2,3}}
%e A319633    {{1},{2},{3}}
%e A319633    {{1,2},{1,3},{2,3}}
%Y A319633 Cf. A006126, A007716, A049311, A059201, A283877, A293606, A316980, A316983, A318099, A319558, A319616-A319646, A300913.
%K A319633 nonn,more
%O A319633 0,3
%A A319633 _Gus Wiseman_, Sep 25 2018