A323820 Number of non-isomorphic connected set-systems covering n vertices with no singletons.

1, 0, 1, 6, 171, 611846, 200253853704319, 263735716028826427334553304608242, 5609038300883759793482640992086670066496449147691597380632107520565546

Offset: 0

Author

Gus Wiseman, Jan 30 2019

Keywords

• nonn

Comments

The labeled case is A323817.

Examples

			Non-isomorphic representatives of the a(3) = 6 set-systems:
  {{1,2,3}}
  {{1,3},{2,3}}
  {{2,3},{1,2,3}}
  {{1,2},{1,3},{2,3}}
  {{1,3},{2,3},{1,2,3}}
  {{1,2},{1,3},{2,3},{1,2,3}}
		

Crossrefs

Cf. A000295, A003465, A016031, A048143, A055621, A293510, A305001, A317795 (not necessarily connected), A323817 (unlabeled case), A323819 (with singletons).

Formula

Inverse Euler transform of A317795.