A009144 - OEIS

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A009144

Expansion of cosh(sin(x))/cos(x).

1, 2, 8, 88, 2176, 78080, 4159616, 307882240, 29920681984, 3710767394816, 571523842998272, 107010484096565248, 23940179383147724800, 6306683724617339961344, 1932337463823712544620544

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..14.

FORMULA

a(n) ~ (2*n)! * (exp(1) + exp(-1)) / (Pi/2)^(2*n+1). - Vaclav Kotesovec, Jan 22 2015

MATHEMATICA

Cosh[ Sin[ x ] ]/Cos[ x ] (* Even Part *)

nn = 20; Table[(CoefficientList[Series[Cosh[Sin[x]]*Sec[x], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* Vaclav Kotesovec, Jan 22 2015 *)

CROSSREFS

Sequence in context: A083831 A134245 A141313 * A132316 A136749 A226321

Adjacent sequences: A009141 A009142 A009143 * A009145 A009146 A009147

KEYWORD

nonn

AUTHOR

R. H. Hardin

EXTENSIONS

Extended and signs tested Mar 15 1997 by Olivier Gérard.

STATUS

approved