A009080 Expansion of e.g.f. cos(x*tan(x)), even terms only.

1, 0, -12, -240, -5936, -155520, -65472, 981903104, 223580862720, 46255608778752, 10060678641587200, 2368138744630923264, 601490101481648443392, 161192778898870464512000, 43208403753541588946141184

Offset: 0

Author

R. H. Hardin

Keywords

• sign

Examples

			cos(x*tan(x)) = 1/0! +0*x^2/2! -12*x^4/4! -240*x^6/6! -5936*x^8/8! -...
		

Links

• G. C. Greubel, Table of n, a(n) for n = 0..240

Programs

Mathematica

With[{nmax = 60}, CoefficientList[Series[Cos[x*Tan[x]], {x, 0, nmax}], x]*Range[0, nmax]!][[1 ;; -1 ;; 2]] (* G. C. Greubel, Jul 24 2018 *)

PARI

x='x+O('x^60); v=Vec(serlaplace(cos(x*tan(x)))); vector(#v\2,n,v[2*n-1]) \\ G. C. Greubel, Jul 24 2018

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997