A304985 Number of labeled clutters (connected antichains) spanning n vertices with singleton edges allowed.

1, 1, 4, 40, 1344, 203136, 495598592, 309065330371840, 14369391920653644779049472

Offset: 0

Author

Gus Wiseman, May 23 2018

Keywords

• nonn

Comments

Only the non-singleton edges are required to form an antichain.

Examples

			The a(2) = 4 clutters:
{{1,2}}
{{1},{1,2}}
{{2},{1,2}}
{{1},{2},{1,2}}
		

Links

• Gus Wiseman, Sequences enumerating clutters, antichains, hypertrees, and hyperforests, organized by labeling, spanning, and allowance of singletons.

Crossrefs

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

Cf. A000372, A006126, A014466, A304997, A304999, A306505, A317674, A319721.

Formula

For n > 1, a(n) = A048143(n) * 2^n.