A304982 - OEIS

A304982

Number of unlabeled clutters (connected antichains) spanning up to n vertices with singleton edges allowed.

1, 2, 5, 19, 137, 3053, 822526

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OFFSET

0,2

COMMENTS

The initial terms 1, 2, 5, 19 are the same as A304981 but the remaining terms differ.

LINKS

FORMULA

Partial sums of A304983.

EXAMPLE

Non-isomorphic representatives of the a(3) = 19 clutters:

{}

{{2},{1,2}}

{{1,3},{2,3}}

{{3},{1,2,3}}

{{1},{2},{1,2}}

{{1,2},{1,3},{2,3}}

{{3},{1,2},{2,3}}

{{3},{1,3},{2,3}}

{{2},{3},{1,2,3}}

{{1},{2},{3},{1,2,3}}

{{2},{3},{1,2},{1,3}}

{{3},{1,2},{1,3},{2,3}}

{{2},{3},{1,3},{2,3}}

{{1},{2},{3},{1,3},{2,3}}

{{2},{3},{1,2},{1,3},{2,3}}

{{1},{2},{3},{1,2},{1,3},{2,3}}

CROSSREFS

KEYWORD

nonn,more

AUTHOR

Gus Wiseman, May 23 2018

EXTENSIONS

a(5)-a(6) from Andrew Howroyd, Aug 14 2019

STATUS

approved