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 A009834 Expansion of e.g.f.: tanh(x)*sin(tan(x)) (even part). 2
 0, 2, -4, 38, -3144, -49526, -10349516, -460714706, -91894143376, -6277401116142, -1574511126111380, -81923064774031562, -27289817479229247448, 10031662078758108490394, 3820037980300331336027556, 3713233478960254473261772350, 1785602965553070049822150781152 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Stefano Spezia, Table of n, a(n) for n = 0..200 MATHEMATICA nmax=200; expan=Series[Tanh[x]*Sin[Tan[x]]/2, {x, 0, 2*nmax}]; Join[{0}, Table[(2n)! Coefficient[expan, x^(2n)], {n, nmax}]] (* Stefano Spezia, Sep 17 2022 *) PROG (PARI) my(x='x+O('x^50), v=Vec(serlaplace(tanh(x)*sin(tan(x))))); concat(0, vector(#v\2, k, v[2*k-1])) \\ Michel Marcus, Sep 17 2022 CROSSREFS Twice A024229. Sequence in context: A009626 A009835 A362411 * A106127 A018992 A098625 Adjacent sequences: A009831 A009832 A009833 * A009835 A009836 A009837 KEYWORD sign AUTHOR R. H. Hardin EXTENSIONS Extended with signs by Olivier Gérard, Mar 15 1997 STATUS approved

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Last modified August 12 13:41 EDT 2024. Contains 375113 sequences. (Running on oeis4.)