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A009229
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E.g.f. exp(sinh(x)*cosh(x)).
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1
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1, 1, 1, 5, 17, 57, 337, 1661, 9697, 68529, 451809, 3570613, 29324913, 247557481, 2348275633, 22399292077, 229227939521, 2476740370529, 27378158737089, 323000223133285, 3912000089144273, 49350756905258905
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,4
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..125
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FORMULA
| a(n)=sum(k=1..n, ((sum(i=0..k, (-1)^i*(k-2*i)^n*binomial(k,i)))*2^(n-2*k))/k!), n>0, a(0)=1. [From Vladimir Kruchinin, May 29 2011]
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MATHEMATICA
| With[{nn=30}, CoefficientList[Series[Exp[Sinh[x]Cosh[x]], {x, 0, nn}], x] Range[0, nn]!] (* From Harvey P. Dale, Sep 23 2011 *)
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PROG
| (Maxima)
a(n):=sum(((sum((-1)^i*(k-2*i)^n*binomial(k, i), i, 0, k))*2^(n-2*k))/k!, k, 1, n); [From Vladimir Kruchinin, May 29 2011]
(Pari) x='x+O('x^66); /* that many terms */
Vec(serlaplace(exp(sinh(x)*cosh(x)))) /* show terms */ /* Joerg Arndt, May 29 2011 */
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CROSSREFS
| Sequence in context: A098184 A054113 A146697 * A010914 A180502 A105392
Adjacent sequences: A009226 A009227 A009228 * A009230 A009231 A009232
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KEYWORD
| nonn,easy
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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.
Corrected definition, Joerg Arndt, May 29 2011.
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