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A339014
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E.g.f.: exp(2 * (exp(x) - 1 - x - x^2 / 2)).
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6
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1, 0, 0, 2, 2, 2, 42, 142, 366, 3082, 18626, 86990, 596158, 4485626, 30214498, 224897662, 1871664190, 15587540042, 134045407458, 1231183979886, 11725017784574, 114812031304986, 1170100796863202, 12371771640238174, 134796972965052350, 1514854948728869354
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OFFSET
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0,4
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LINKS
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FORMULA
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a(0) = 1; a(n) = 2 * Sum_{k=3..n} binomial(n-1,k-1) * a(n-k).
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MATHEMATICA
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nmax = 25; CoefficientList[Series[Exp[2 (Exp[x] - 1 - x - x^2/2)], {x, 0, nmax}], x] Range[0, nmax]!
a[0] = 1; a[n_] := a[n] = 2 Sum[Binomial[n - 1, k - 1] a[n - k], {k, 3, n}]; Table[a[n], {n, 0, 25}]
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PROG
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(PARI) my(x='x+O('x^30)); Vec(serlaplace(exp(2 * (exp(x) - 1 - x - x^2/2)))) \\ Michel Marcus, Nov 19 2020
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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