A304996 Number of unlabeled antichains of finite sets spanning up to n vertices with singleton edges allowed.

1, 2, 6, 24, 166, 3266, 826308

Offset: 0

Author

Gus Wiseman, May 23 2018

Keywords

• nonn
• more

Examples

			Non-isomorphic representatives of the a(3) = 24 antichains:
{}
{{1}}
{{1,2}}
{{1,2,3}}
{{1},{2}}
{{2},{1,2}}
{{3},{1,2}}
{{3},{1,2,3}}
{{1,3},{2,3}}
{{1},{2},{3}}
{{1},{2},{1,2}}
{{2},{3},{1,3}}
{{2},{3},{1,2,3}}
{{3},{1,2},{2,3}}
{{3},{1,3},{2,3}}
{{1,2},{1,3},{2,3}}
{{1},{2},{3},{2,3}}
{{1},{2},{3},{1,2,3}}
{{2},{3},{1,2},{1,3}}
{{2},{3},{1,3},{2,3}}
{{3},{1,2},{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

Partial sums of A304997.

Cf. A006126, A261005, A304997, A304998, A304999, A305000, A305001.

Cf. A000372, A014466, A293993, A319639, A319721, A326704, A326972.

Extensions

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