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A012748
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Expansion of e.g.f. sec(arctanh(x)*cos(x)), only even powers.
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1
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1, 1, 1, 25, 3617, 340145, 40490657, 7034559753, 1668333374913, 504856533178465, 189500285350524865, 86696156445549770233, 47524548345395009982689, 30739504895562596416971025, 23162222253680333719652996449, 20112913566033287819336502367465, 19939158697176271310635403636418945
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OFFSET
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0,4
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LINKS
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EXAMPLE
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E.g.f. = 1 + x^2/2! + x^4/4! + 25*x^6/6! + 3617*x^8/8! + ...
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MATHEMATICA
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nmax=32; DeleteCases[CoefficientList[Series[Sec[ArcTanh[x]Cos[x]], {x, 0, nmax}], x], 0](2Range[0, nmax/2])! (* Stefano Spezia, Jun 21 2024 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Patrick Demichel (patrick.demichel(AT)hp.com)
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EXTENSIONS
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STATUS
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approved
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