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
KEYWORD
nonn
AUTHOR
Gus Wiseman, Aug 11 2019
STATUS
approved