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A309667
Number of non-isomorphic connected set-systems on up to n vertices.
2
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
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.
Sequence in context: A193323 A238752 A099137 * A059586 A160968 A329704
KEYWORD
nonn
AUTHOR
Gus Wiseman, Aug 11 2019
STATUS
approved