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A293607
Number of unlabeled clutters of weight n.
12
1, 1, 1, 1, 2, 2, 7, 8, 23, 42
OFFSET
0,5
COMMENTS
A clutter is a connected antichain of finite sets. The weight of a clutter is the sum of cardinalities of its edges.
EXAMPLE
Non-isomorphic representatives of the a(7) = 8 clutters are:
((1234567)),
((12)(13456)), ((123)(1245)), ((123)(1456)),
((12)(13)(145)), ((12)(13)(234)), ((12)(13)(245)), ((13)(24)(125)).
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Gus Wiseman, Oct 13 2017
STATUS
approved