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Search: id:A103869
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| A103869 |
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Number of unlabeled graphs with n nodes whose adjacency matrix has nonzero even determinant. |
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+0
1
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OFFSET
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1,5
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COMMENT
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a(n) = A140981(n) - A133206(n).
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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 && Mod[Det[ToAdjacencyMatrix[lg[[ # ]]]], 2] == 0 &]]]]; k
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CROSSREFS
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Cf. A133206, A140981, A141040, A109717, A000088.
Adjacent sequences: A103866 A103867 A103868 this_sequence A103870 A103871 A103872
Sequence in context: A041178 A119159 A041415 this_sequence A041753 A042191 A042729
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KEYWORD
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more,nonn
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AUTHOR
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Tanya Khovanova (tanyakh(AT)yahoo.com), Aug 29 2008
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