A304918 Number of labeled antichain hyperforests spanning a subset of {1,...,n}.

1, 2, 5, 18, 104, 943, 12133, 203038, 4177755, 101922814, 2874725600, 92009680557, 3294276613933, 130446181101044, 5660055256165565, 267044522107706072, 13611243187516647324, 745329728016955480687, 43636132793651444511809, 2719977663069107176768790

Offset

0,2

Links

Table of n, a(n) for n=0..19.

Formula

Binomial transform of A134954.

Example

The a(3) = 18 hyperforests are the following:
{{1,2,3}}      {{2,3}}    {{1,3}}    {{1,2}}    {{3}}   {{2}}   {{1}}   {}
{{1,3},{2,3}}  {{2},{3}}  {{1},{3}}  {{1},{2}}
{{1,2},{2,3}}
{{1,2},{1,3}}
{{3},{1,2}}
{{2},{1,3}}
{{1},{2,3}}
{{1},{2},{3}}

Crossrefs

Cf. A030019, A035053, A048143, A134954, A134955, A134957, A134956, A134957, A134959, A144959, A303838, A304716, A304717, A304867, A304911, A304912.

Sequence in context: A005639 A093730 A366449 * A007769 A174122 A005805

Adjacent sequences: A304915 A304916 A304917 * A304919 A304920 A304921

Keyword

nonn

Author

Gus Wiseman, May 21 2018

Status

approved