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A012303
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Expansion of e.g.f. sech(sin(x)*sin(x)), even powers only.
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1
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1, 0, -12, 240, 4368, -942720, 42639168, 8638506240, -2287049555712, 38746394603520, 145600412857955328, -42974022434701332480, -7760313189299657306112, 11863589839842518338928640
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OFFSET
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0,3
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LINKS
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EXAMPLE
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E.g.f. = 1 - 12*x^4/4! + 240*x^6/6! + 4368*x^8/8! + ...
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MAPLE
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seq(coeff(series(factorial(n)*sech(sin(x)*sin(x)), x, n+1), x, n), n = 0 .. 26, 2); # Muniru A Asiru, Oct 26 2018
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MATHEMATICA
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With[{nn = 100}, CoefficientList[Series[Sech[Sin[x]^2], {x, 0, nn}], x] Range[0, nn]!][[1 ;; ;; 2]] (* G. C. Greubel, Oct 25 2018 *)
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PROG
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(PARI) x='x+O('x^50); v=Vec(serlaplace(1/cosh(sin(x)*sin(x)))); vector(#v\2, n, v[2*n-1]) \\ G. C. Greubel, Oct 25 2018
(Magma) m:=30; R<x>:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!( 1/Cosh(Sin(x)^2) )); [Factorial(2*n)*b[2*n+1]: n in [0..Floor((m-2)/2)]]; // G. C. Greubel, Oct 25 2018
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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Patrick Demichel (patrick.demichel(AT)hp.com)
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STATUS
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approved
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