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A009110
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Expansion of e.g.f. cos(x)/cosh(tan(x)), even powers only.
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1
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1, -2, 4, 32, 400, -3680, -719168, -45313024, -1201882880, 190738937344, 41876315935744, 3729103532367872, -442609357053390848, -294584246423093633024, -75554765797484141625344, -7698772402123265223688192, 3712165683571701387680088064
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OFFSET
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0,2
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LINKS
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G. C. Greubel, Table of n, a(n) for n = 0..243
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MATHEMATICA
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With[{nn=40}, Take[CoefficientList[Series[Cos[x]/Cosh[Tan[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, May 06 2016 *)
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PROG
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(PARI) x='x+O('x^50); v=Vec(serlaplace(cos(x)/cosh(tan(x)))); vector(#v\2, n, v[2*n-1]) \\ G. C. Greubel, Jul 26 2018
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CROSSREFS
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Sequence in context: A085055 A075070 A144937 * A225170 A134958 A101460
Adjacent sequences: A009107 A009108 A009109 * A009111 A009112 A009113
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KEYWORD
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sign
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AUTHOR
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R. H. Hardin
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EXTENSIONS
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Extended with signs by Olivier Gérard, Mar 15 1997
More terms from and prior Mathematica program replaced by Harvey P. Dale, May 06 2016
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STATUS
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approved
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