%I
%S 1,1,1,1,2,2,7,8,23,42
%N Number of unlabeled clutters of weight n.
%C A clutter is a connected antichain of finite sets. The weight of a clutter is the sum of cardinalities of its edges.
%e Nonisomorphic representatives of the a(7) = 8 clutters are:
%e ((1234567)),
%e ((12)(13456)), ((123)(1245)), ((123)(1456)),
%e ((12)(13)(145)), ((12)(13)(234)), ((12)(13)(245)), ((13)(24)(125)).
%Y Cf. A006126, A007716, A048143, A049311, A283877, A293606.
%K nonn,more
%O 0,5
%A _Gus Wiseman_, Oct 13 2017
