OFFSET
0,3
COMMENTS
We define a hypergraph to be any finite set of finite nonempty sets. A hypergraph is regular if all vertices have the same degree.
EXAMPLE
The a(3) = 4 edge-sets:
{}
{{1,2,3}}
{{1,2},{1,3},{2,3}}
{{1,2},{1,3},{2,3},{1,2,3}}
MATHEMATICA
Table[Sum[SeriesCoefficient[Product[1+Times@@x/@s, {s, Subsets[Range[n], {2, n}]}], Sequence@@Table[{x[i], 0, k}, {i, n}]], {k, 0, 2^n-n-1}], {n, 1, 5}]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Gus Wiseman, Dec 23 2018
STATUS
approved