A109717 Number of unlabeled graphs with n nodes and an invertible adjacency matrix.

0, 1, 1, 4, 9, 57, 354, 5795, 141494, 7866527, 728952205

Offset: 1

Author

Tanya Khovanova, Aug 17 2008

Keywords

• hard
• more
• nonn

Programs

Mathematica

k = {}; For[i = 1, i < 8, i++, lg = ListGraphs[i] ; len = Length[lg]; k = Append[k, Length[Select[Range[len], Det[ToAdjacencyMatrix[lg[[ # ]]]] != 0 &]]]]; k

Extensions

Terms a(8)-a(10) from Steve Butler, Jun 21 2013

Term a(11) from Steve Butler, Aug 21 2013