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A009554
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Expansion of e.g.f. sin(x)/cos(sinh(x)) (odd powers only).
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1
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1, 2, 36, 944, 45136, 3263072, 334656960, 46199442176, 8260388524288, 1857027989588480, 512693973356712960, 170529221696594702336, 67257392621575577522176, 31036094843772953163063296
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n) ~ (2*n-1)! * 4 * sin(arcsinh(Pi/2)) / (sqrt(4+Pi^2) * (arcsinh(Pi/2))^(2*n)). - Vaclav Kotesovec, Jan 23 2015
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MATHEMATICA
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With[{nn=30}, Take[CoefficientList[Series[Sin[x]/Cos[Sinh[x]], {x, 0, nn}], x]Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Jan 19 2012 *)
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PROG
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(PARI) x='x+O('x^50); v=Vec(serlaplace(sin(x)/cos(sinh(x)))); vector((#v-1)\2 , n, v[2*n-1]) \\ G. C. Greubel, Jan 20 2018
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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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