A304983 Number of unlabeled clutters (connected antichains) spanning n vertices with singleton edges allowed.

1, 1, 3, 14, 118, 2916, 819473

Offset

0,3

Links

Table of n, a(n) for n=0..6.

Formula

Inverse Euler transform of A304997. - Andrew Howroyd, Aug 14 2019

Example

Non-isomorphic representatives of the a(3) = 14 clutters:
  {{1,2,3}}
  {{1,3},{2,3}}
  {{3},{1,2,3}}
  {{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

Cf. A048143, A198085, A261006, A304912, A304981, A304982, A304983, A304984, A304985, A304986, A304997.

Sequence in context: A122081 A007140 A161936 * A349013 A260887 A127850

Adjacent sequences: A304980 A304981 A304982 * A304984 A304985 A304986

Keyword

nonn,more

Author

Gus Wiseman, May 23 2018

Extensions

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

Status

approved