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A009747
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E.g.f. tan(x)*sinh(x) (even powers only).
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9
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0, 2, 12, 142, 3192, 116282, 6219972, 458790022, 44625674352, 5534347077362, 852334810990332, 159592488559874302, 35703580441464231912, 9405575479317650316842, 2881823738166957609703092, 1016124476854507687644180982, 408525180980254462140262747872, 185768439922172208338308590282722
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) ~ (2*n)! * 4^(n+1) * sinh(Pi/2) / Pi^(2*n+1). - Vaclav Kotesovec, Jan 24 2015
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MATHEMATICA
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nn = 20; Table[(CoefficientList[Series[Sinh[x]*Tan[x], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* Vaclav Kotesovec, Jan 24 2015 *)
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PROG
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(Sage) # Generalized algorithm of L. Seidel (1877)
R = []; A = {-1:0, 0:0}
k = 0; e = 1
for i in range(2*n) :
Am = 1 if e == -1 else 0
A[k + e] = 0
e = -e
for j in (0..i) :
Am += A[k]
A[k] = Am
k += e
if e == -1 : R.append(A[-i//2])
return R
(PARI) x='x+O('x^66); v=Vec(serlaplace(tan(x)*sinh(x))); concat([0], vector(#v\2, n, v[2*n-1])) \\ Joerg Arndt, Apr 26 2013
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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