A304986 - OEIS

A304986

Number of labeled clutters (connected antichains) spanning some subset of {1,...,n}, if clutters of the form {{x}} are allowed for any vertex x.

1, 2, 4, 12, 115, 6834, 7783198, 2414627236078, 56130437209370100252471

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

LINKS

FORMULA

a(n > 0) = A198085(n) + 1.

a(n) = A305005(n) + n.

EXAMPLE

The a(3) = 12 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