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A009613
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E.g.f. sinh(tan(x)*tan(x)) (even powers only).
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3
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0, 2, 16, 392, 21376, 1875872, 227105536, 35750690432, 7110343684096, 1750588208886272, 523940264885702656, 187423773435078920192, 78905518064423548911616, 38568578386644134655598592
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n)=sum(m=0..n, 1/(2*m+1)!*sum(j=4*m+2..2*n, binomial(j-1,4*m+1)*j!*2^(2*n-j)*(-1)^(n+1+j)*stirling2(2*n,j))). [From Vladimir Kruchinin, Jun 11 2011]
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EXAMPLE
| sinh(tan(x)*tan(x))=2/2!*x^2+16/4!*x^4+392/6!*x^6+21376/8!*x^8...
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PROG
| (Maxima)
a(n):=sum(1/(2*m+1)!*sum(binomial(j-1, 4*m+1)*j!*2^(2*n-j)*(-1)^(n+1+j)*stirling2(2*n, j), j, 4*m+2, 2*n), m, 0, n); [From Vladimir Kruchinin, Jun 11 2011]
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CROSSREFS
| Sequence in context: A002474 A172149 A012390 * A012388 A012752 A188904
Adjacent sequences: A009610 A009611 A009612 * A009614 A009615 A009616
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KEYWORD
| nonn
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AUTHOR
| R. H. Hardin (rhhardin(AT)att.net)
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EXTENSIONS
| Extended and signs tested Mar 15 1997 by Olivier Gerard.
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