A305005 - OEIS

A305005

Number of labeled clutters (connected antichains) spanning some subset of {1,...,n} without singleton edges.

1, 1, 2, 9, 111, 6829, 7783192, 2414627236071, 56130437209370100252463

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OFFSET

0,3

LINKS

FORMULA

Binomial transform of A048143 if we assume A048143(1) = 0.

a(n) = A198085(n) - n + 1. - Gus Wiseman, Jun 11 2018

EXAMPLE

The a(3) = 9 clutters:

{}

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

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

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

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

CROSSREFS

KEYWORD

nonn

AUTHOR

Gus Wiseman, May 23 2018

STATUS

approved