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A009801
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E.g.f. tanh(sin(x)*sin(x)) (even powers only).
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2
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0, 2, -8, -208, 13312, -80128, -84819968, 9993992192, 759755210752, -560066285928448, 72155207745667072, 37670722015948439552, -22728912607776874692608, 734502681629602026094592
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n)=2*sum(m=1..2*n, ((sum(k=1..m, (-1)^(k+1)*k!*2^(2*n-m-k)*stirling2(m,k)))*sum(i=0..m, (i-m)^(2*n)*binomial(2*m,i)*(-1)^(n+m-i)))/(m!)). [From Vladimir Kruchinin, Jun 28 2011]
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EXAMPLE
| tanh(sin(x)*sin(x)) = 2/2!*x^2-8/4!*x^4-208/6!*x^6+13312/8!*x^8...
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PROG
| (Maxima)
a(n):=2*sum(((sum((-1)^(k+1)*k!*2^(2*n-m-k)*stirling2(m, k), k, 1, m))*sum((i-m)^(2*n)*binomial(2*m, i)*(-1)^(n+m-i), i, 0, m))/(m!), m, 1, 2*n); [From Vladimir Kruchinin, Jun 28 2011]
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CROSSREFS
| Sequence in context: A012539 A012535 A012300 * A012297 A000893 A030177
Adjacent sequences: A009798 A009799 A009800 * A009802 A009803 A009804
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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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