A003708 Expansion of tan(log(1+x)).

0, 1, -1, 4, -18, 110, -810, 7040, -70280, 792200, -9945000, 137550400, -2077719600, 34026132400, -600433397200, 11356783360000, -229193571984000, 4915556301968000, -111644265232656000, 2676908220027392000

Offset: 0

Author

R. H. Hardin, Simon Plouffe

Keywords

• sign

References

• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..200

Programs

Mathematica

With[{nn=20},CoefficientList[Series[Tan[Log[1+x]],{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, May 28 2013 *)

Formula

a(n) ~ n! / (exp(Pi/2) * (exp(-Pi/2)-1)^(n+1)). - Vaclav Kotesovec, Feb 16 2015