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Search: id:A109717
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| A109717 |
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Number of unlabeled graphs with n nodes and an invertible adjacency matrix. |
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+0
4
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OFFSET
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1,4
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MATHEMATICA
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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
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CROSSREFS
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Sequence in context: A009276 A086692 A069507 this_sequence A013571 A002942 A028908
Adjacent sequences: A109714 A109715 A109716 this_sequence A109718 A109719 A109720
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KEYWORD
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hard,more,nonn
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AUTHOR
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Tanya Khovanova (tanyakh(AT)yahoo.com), Aug 17 2008
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