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A297029
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Number of edge covers in the n-cocktail party graph.
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2
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0, 7, 2902, 14872877, 1057937802444, 1139547636041211251, 19276901022645375031039586, 5187230738913145148610293591969497, 22294621657566842766129181417308087584893464, 1532378628985463601567919431617165851656712130496565087
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n) = Sum_{i=0..n} Sum_{j=0, 2*(n-i)} (-1)^(i+j)*binomial(n, i)*binomial(2*(n-i), j)*2^(binomial(2*n-j, 2)-i). - Andrew Howroyd, Dec 27 2017
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MATHEMATICA
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a[n_] := Sum[(-1)^(i + j)*Binomial[n, i]*Binomial[2*(n - i), j] * 2^(Binomial[2*n - j, 2] - i), {i, 0, n}, {j, 0, 2*(n - i)}];
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PROG
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(PARI) a(n)={sum(i=0, n, sum(j=0, 2*(n-i), (-1)^(i+j)*binomial(n, i)*binomial(2*(n-i), j)*2^(binomial(2*n-j, 2)-i)))} \\ Andrew Howroyd, Dec 27 2017
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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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