A013208 Expansion of e.g.f. log(sech(x) + tanh(x)).

0, 1, -2, 3, -8, 45, -272, 1743, -13568, 125625, -1290752, 14554683, -181296128, 2473184805, -36501112832, 579439207623, -9859508338688, 179018972217585, -3453141256896512, 70518070842040563

Offset: 0

Author

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

Keywords

• sign

Examples

			x - 2/2!*x^2 + 3/3!*x^3 - 8/4!*x^4 + 45/5!*x^5 ...
		

Programs

Mathematica

With[{nn=20},CoefficientList[Series[Log[Sech[x]+Tanh[x]],{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Oct 22 2023 *)

Extensions

a(0)=0 inserted and title improved by Sean A. Irvine, Aug 01 2018