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A009273
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E.g.f. exp(x*tanh(x)) (even powers only).
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0
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1, 2, 4, -24, 400, -5600, -103872, 26975872, -3438685952, 417995260416, -51382607559680, 5994623640856576, -454930757753597952, -94991612229069430784, 81515752167646959124480
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n)=sum(m=0..2*n, binomial(2*n,m)*sum(k=0..2*n-2*m, binomial(k+m-1,m-1)*(k+m)!*(-1)^(k)*2^(2*n-2*m-k)*stirling2(2*n-m,k+m))), n>0, a(0)=1. [From Vladimir Kruchinin, Jun 06 2011]
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MATHEMATICA
| Exp[ Tanh[ x ]*x ] (* Even Part *)
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PROG
| (Maxima)
a(n):=sum(binomial(2*n, m)*sum(binomial(k+m-1, m-1)*(k+m)!*(-1)^(k)*2^(2*n-2*m-k)*stirling2(2*n-m, k+m), k, 0, 2*n-2*m), m, 0, 2*n); [From Vladimir Kruchinin, Jun 06 2011]
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CROSSREFS
| Sequence in context: A047677 A030276 A081476 * A128299 A143672 A001510
Adjacent sequences: A009270 A009271 A009272 * A009274 A009275 A009276
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KEYWORD
| sign
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AUTHOR
| R. H. Hardin (rhhardin(AT)att.net)
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EXTENSIONS
| Extended with signs Mar 15 1997 by Olivier Gerard.
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