OFFSET
0,4
COMMENTS
A hypergraph is a T_0 hypergraph if for every two distinct nodes there exists a hyperedge containing one but not the other node.
FORMULA
T(n,m) = Sum_{i=0..m} stirling1(m, i)*binomial(2^i+n-1, n).
EXAMPLE
Triangle starts:
1, 1;
1, 2, 2;
1, 3, 7, 12, 12;
1, 4, 16, 68, 292, 1120, 3360, 6720, 6720;
...
There are 7 2-node T_0-hypergraphs with 2 hyperedges: {{}, {1}}, {{}, {2}}, {{1}, {1}}, {{1}, {2}}, {{1}, {1, 2}}, {{2}, {2}} and {{2}, {1, 2}}.
CROSSREFS
KEYWORD
easy,nonn,tabf
AUTHOR
Vladeta Jovovic, Goran Kilibarda, Jan 23 2001
STATUS
approved