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A327379
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Number of labeled non-mating-type graphs with n vertices.
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2
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0, 1, 4, 32, 436, 11292, 545784, 49826744, 8647819328, 2876819527744, 1848998498567936, 2312324942899031040, 5659406410382924819712, 27230994319259100289485568, 258465217554621196991878652416, 4851552662579126853087143276476928
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OFFSET
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1,3
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COMMENTS
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A mating-type graph has all different rows in its adjacency matrix.
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LINKS
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FORMULA
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MATHEMATICA
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Table[Length[Select[Subsets[Subsets[Range[n], {2}]], !UnsameQ@@AdjacencyMatrix[Graph[Range[n], #]]&]], {n, 5}]
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PROG
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(PARI) a(n) = {2^binomial(n, 2) - sum(k=0, n, stirling(n, k, 1)*2^binomial(k, 2))} \\ Andrew Howroyd, Sep 11 2019
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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