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