A009689 Expansion of tan(tan(log(1+x))).

0, 1, -1, 6, -30, 236, -2100, 22712, -279776, 3914264, -60987960, 1048837952, -19714584912, 402125014864, -8843878384432, 208597059565312, -5252013479541120, 140581822236104576, -3986197501417665408

Offset

0,4

Links

Table of n, a(n) for n=0..18.

Mathematica

With[{nn=20}, CoefficientList[Series[Tan[Tan[Log[1+x]]], {x, 0, nn}], x] Range[ 0, nn]!] (* Harvey P. Dale, May 14 2019 *)

Crossrefs

Sequence in context: A209070 A259820 A126751 * A228873 A366809 A133668

Adjacent sequences: A009686 A009687 A009688 * A009690 A009691 A009692

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Previous Mathematica program replaced by Harvey P. Dale, May 14 2019

Status

approved