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A293607 Number of unlabeled clutters of weight n. 12

%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 Non-isomorphic 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

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Last modified May 11 02:34 EDT 2021. Contains 343784 sequences. (Running on oeis4.)