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A297215 Expansion of e.g.f. exp(cos(tan(x))-1) (even powers only). 2
1, -1, -4, -7, 1003, 64836, 3350349, 104475395, -12291888052, -4268687337603, -877769324284177, -139938933307889412, -9581950082738688167, 6333750977985105075527, 4837035706491587870342140, 2439859866050865745230242689, 1033093869484852949078289394195 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..16.

FORMULA

a(n) = (2*n)! * [x^(2*n)] exp(cos(tan(x))-1).

EXAMPLE

exp(cos(tan(x))-1) = 1 - x^2/2! - 4*x^4/4! - 7*x^6/6! + 1003*x^8/8! + 64836*x^10/10! + ...

MATHEMATICA

nmax = 16; Table[(CoefficientList[Series[Exp[Cos[Tan[x]] - 1], {x, 0, 2 nmax}], x] Range[0, 2 nmax]!)[[n]], {n, 1, 2 nmax + 1, 2}]

CROSSREFS

Cf. A003710, A009074, A009201, A009202, A009203, A009204, A009238, A009239, A009240, A009241, A009254, A297214.

Sequence in context: A126577 A236288 A073164 * A134900 A028583 A305744

Adjacent sequences:  A297212 A297213 A297214 * A297216 A297217 A297218

KEYWORD

sign

AUTHOR

Ilya Gutkovskiy, Dec 27 2017

STATUS

approved

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Last modified October 17 08:36 EDT 2019. Contains 328107 sequences. (Running on oeis4.)