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A054950
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Number of labeled semi-strong digraphs on n nodes with an even number of components.
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1
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0, 1, 3, 76, 8220, 3418216, 5156362008, 28205998918336, 571801003320734400, 44006976469834509225856, 13095012982298536065778624128, 15245644966564725709168192019570176, 69953982671396722666217758540260522923520, 1270721533437616701720124856867026526491583190016
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OFFSET
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1,3
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LINKS
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FORMULA
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MATHEMATICA
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A054948[0] = 1; A054948[n_] := A054948[n] = Module[{A}, A = 1 + Sum[ A054948[k]*x^k/k!, {k, 1, n - 1}]; n!*SeriesCoefficient[Sum[2^(k^2 - k)*x^k/k!/(A /. x -> 2^k*x) , {k, 0, n}], {x, 0, n}]];
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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