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A109717
Number of unlabeled graphs with n nodes and an invertible adjacency matrix.
3
0, 1, 1, 4, 9, 57, 354, 5795, 141494, 7866527, 728952205
OFFSET
1,4
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
CROSSREFS
Sequence in context: A360514 A358446 A152284 * A197859 A197997 A309444
KEYWORD
hard,more,nonn
AUTHOR
Tanya Khovanova, Aug 17 2008
EXTENSIONS
Terms a(8)-a(10) from Steve Butler, Jun 21 2013
Term a(11) from Steve Butler, Aug 21 2013
STATUS
approved