A304984 Number of labeled clutters (connected antichains) spanning some subset of {1,...,n} with singleton edges allowed.

1, 2, 7, 56, 1533, 210302, 496838435, 309068803876372, 14369391923126181310256825

Offset

0,2

Links

Table of n, a(n) for n=0..8.

Formula

Binomial transform of A304985(n > 0).

Example

The a(2) = 7 clutters:
  {}
  {{1}}
  {{2}}
  {{1,2}}
  {{1},{1,2}}
  {{2},{1,2}}
  {{1},{2},{1,2}}

Crossrefs

Cf. A048143, A198085, A261006, A304912, A304981, A304982, A304983, A304984, A304985, A304986.

Sequence in context: A211209 A363205 A271440 * A002658 A175818 A034939

Adjacent sequences: A304981 A304982 A304983 * A304985 A304986 A304987

Keyword

nonn

Author

Gus Wiseman, May 23 2018

Status

approved