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A368268
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Expansion of e.g.f. exp(-x) / (1 - 2*x*exp(x)).
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2
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1, 1, 9, 71, 817, 11599, 197881, 3938087, 89569761, 2291869727, 65159228521, 2037767466679, 69521938950289, 2569515452879855, 102274007835523161, 4361566914028222919, 198403133940750790081, 9589223805173365594687, 490729273233730201604809
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OFFSET
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0,3
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LINKS
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FORMULA
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a(n) = n! * Sum_{k=0..n} 2^(n-k) * (n-k-1)^k / k!.
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PROG
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(PARI) a(n) = n!*sum(k=0, n, 2^(n-k)*(n-k-1)^k/k!);
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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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