A309667 Number of non-isomorphic connected set-systems on up to n vertices.

1, 2, 5, 35, 1947, 18664537, 12813206150464222, 33758171486592987151274638818642016, 1435913805026242504952006868879460423801146743462225386062178112354069599

Offset: 0

Author

Gus Wiseman, Aug 11 2019

Keywords

• nonn

Comments

A set-system is a finite set of finite nonempty sets.

Examples

			Non-isomorphic representatives of the a(0) = 1 through a(2) = 5 set-systems:
  {}  {}     {}
      {{1}}  {{1}}
             {{1,2}}
             {{2},{1,2}}
             {{1},{2},{1,2}}
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..12

Crossrefs

The covering case is A323819 (first differences).

The BII-numbers of connected set-systems are A326749.

The labeled version is A326964.

Cf. A000371, A000612, A001187, A007718, A058891, A092918, A261006, A300913, A323818.