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Search: id:A088789
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| A088789 |
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E.g.f.: REVERT(2*x/(1+exp(x))) = sum(n>=0, a(n)*x^n/n!). |
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+0
2
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| 0, 1, 1, 3, 14, 90, 738, 7364, 86608, 1173240, 17990600, 308055528, 5826331440, 120629547584, 2713659864832, 65909241461760, 1718947213795328, 47912968352783232, 1421417290991105664, 44717945211445216640
(list; graph; listen)
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OFFSET
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0,4
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REFERENCES
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R. W. Whitty, Rook polynomials on two-dimensional surfaces..., Discrete Math., 308 (2008), 674-683.
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LINKS
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Alois P. Heinz, Table of n, a(n) for n = 0..100
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FORMULA
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E.g.f.: x/2-LambertW(-1/2*x*exp(1/2*x)). - Vladeta Jovovic (vladeta(AT)eunet.rs), Feb 12 2008
a(n) = (1/2^n)*Sum_{k=1..n} binomial(n,k)*k^(n-1)= A038049(n)/2^n, n>1. - Vladeta Jovovic (vladeta(AT)eunet.rs), Feb 12 2008
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MAPLE
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a := n-> coeff(series (x/2-LambertW(-1/2*x*exp(1/2*x)), x=0, n+1), x, n)*n!: seq (a(n), n=0..25); [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Aug 14 2008]
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PROGRAM
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(PARI) a(n)=local(A); if(n<0, 0, A=x+O(x^n); n!*polcoeff(serreverse(2*x/(1+exp(x))), n))
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CROSSREFS
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Sequence in context: A007549 A081005 A074518 this_sequence A029767 A120056 A125788
Adjacent sequences: A088786 A088787 A088788 this_sequence A088790 A088791 A088792
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Oct 15 2003
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EXTENSIONS
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More terms from Alois P. Heinz (heinz(AT)hs-heilbronn.de), Aug 14 2008
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