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

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

Offset: 0

Author

Gus Wiseman, May 23 2018

Keywords

• nonn
• more

Examples

			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.

Formula

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

Extensions

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