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A308351
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For n >= 2, a(n) = n*u(n-1) + n*(n-1)*u(n-2), where u = A292932; a(1)=1.
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1
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1, 4, 18, 128, 1090, 11232, 134806, 1849696, 28550538, 489656720, 9237631150, 190115847792, 4238752713442, 101775333547552, 2618244556598310, 71846664091504064, 2094748778352174202, 64666725024407102064, 2107224874854168508126, 72279858915240296971600
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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) ~ n! * (r-2) / ((r-1) * (r-3)^n), where r = -LambertW(-1, -2*exp(-3)). - Vaclav Kotesovec, Jun 05 2019
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MAPLE
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E:= x*(1 + x)/(3 - 2*exp(x) + x):
S:= series(E, x, 51):
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MATHEMATICA
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nmax = 20; Rest[CoefficientList[Series[x*(1 + x)/(3 - 2*E^x + x), {x, 0, nmax}], x] * Range[0, nmax]!] (* Vaclav Kotesovec, Jun 05 2019 *)
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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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