A009074 Expansion of e.g.f. cos(tan(x))/exp(x).

1, -1, 0, 2, -12, 44, -216, 944, -5296, 27632, -168128, 975072, -5391680, 27882048, 38412672, -1986004224, 61881368832, -850359527680, 16576603568128, -222801125934592, 4120672559178752, -57863671042155520

Offset: 0

Author

R. H. Hardin

Keywords

• sign
• easy

Links

• G. C. Greubel, Table of n, a(n) for n = 0..250

Programs

Magma

m:=30; R:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!(Cos(Tan(x))/Exp(x))); [Factorial(n-1)*b[n]: n in [1..m]]; // G. C. Greubel, Jul 24 2018

Mathematica

With[{nmax = 30}, CoefficientList[Series[Cos[Tan[x]]/Exp[x], {x, 0, nmax}], x]*Range[0, nmax]!] (* G. C. Greubel, Jul 24 2018 *)

PARI

x='x+O('x^30); Vec(serlaplace(cos(tan(x))/exp(x))) \\ G. C. Greubel, Jul 24 2018

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997