A293607 Number of unlabeled clutters of weight n.

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.

Links

Table of n, a(n) for n=0..9.

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

Cf. A006126, A007716, A048143, A049311, A283877, A293606.

Sequence in context: A168160 A005300 A019087 * A026563 A062305 A155063

Adjacent sequences: A293604 A293605 A293606 * A293608 A293609 A293610

Keyword

nonn,more

Author

Gus Wiseman, Oct 13 2017

Status

approved