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A293607 Number of unlabeled clutters of weight n. 12
1, 1, 1, 1, 2, 2, 7, 8, 23, 42 (list; graph; refs; listen; history; text; internal format)
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

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Last modified April 16 17:01 EDT 2021. Contains 343050 sequences. (Running on oeis4.)