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

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

Offset

0,2

Comments

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

Links

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

Example

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}}

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.

Sequence in context: A193323 A238752 A099137 * A059586 A160968 A329704

Adjacent sequences: A309664 A309665 A309666 * A309668 A309669 A309670

Keyword

nonn

Author

Gus Wiseman, Aug 11 2019

Status

approved