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A012303 Expansion of e.g.f. sech(sin(x)*sin(x)), even powers only. 1
1, 0, -12, 240, 4368, -942720, 42639168, 8638506240, -2287049555712, 38746394603520, 145600412857955328, -42974022434701332480, -7760313189299657306112, 11863589839842518338928640 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..225

EXAMPLE

E.g.f. = 1 - 12*x^4/4! + 240*x^6/6! + 4368*x^8/8! + ...

MAPLE

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

MATHEMATICA

With[{nn = 100}, CoefficientList[Series[Sech[Sin[x]^2], {x, 0, nn}], x] Range[0, nn]!][[1 ;; ;; 2]] (* G. C. Greubel, Oct 25 2018 *)

PROG

(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

CROSSREFS

Sequence in context: A012544 A009052 A213449 * A119837 A012538 A006588

Adjacent sequences:  A012300 A012301 A012302 * A012304 A012305 A012306

KEYWORD

sign

AUTHOR

Patrick Demichel (patrick.demichel(AT)hp.com)

STATUS

approved

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Last modified May 22 00:25 EDT 2019. Contains 323472 sequences. (Running on oeis4.)