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A175925
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a(n) = (2*n+1)*(n+1)!.
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4
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1, 6, 30, 168, 1080, 7920, 65520, 604800, 6168960, 68947200, 838252800, 11017036800, 155675520000, 2353813862400, 37922556672000, 648606486528000, 11737685127168000, 224083079700480000, 4500868715126784000
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OFFSET
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0,2
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COMMENTS
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The denominators of the Taylor expansion coefficients of the double integral d(u) = int_0^1 dx int_0^1 dy exp(-u^2*(x-y)^2) = Sum_{n>=0} (-1)^n*u^(2n)/a(n).
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LINKS
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FORMULA
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Sum_{n>=0} 1/a(n) = sqrt(Pi)*erfi(1) + 1 - e.
Sum_{n>=0} (-1)^n/a(n) = sqrt(Pi)*erf(1) - 1 + 1/e. (End)
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MAPLE
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A := proc(n) (2*n+1)*(n+1)! ; end proc:
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MATHEMATICA
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PROG
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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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STATUS
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approved
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