A012452 arctanh(arctan(x)*tan(x))=2/2!*x^2+400/6!*x^6-2688/8!*x^8...

0, 2, 0, 400, -2688, 1873408, -60938240, 49450805248, -4291105193984, 4345356280528896, -769792296435580928, 962815994229666349056, -298377426990773724774400, 452668537171760533299265536

Offset

0,2

Links

Table of n, a(n) for n=0..13.

Mathematica

With[{nn=30}, Take[CoefficientList[Series[ArcTanh[ArcTan[x]*Tan[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Ray Chandler, Nov 28 2016 *)

Crossrefs

Sequence in context: A012446 A324687 A012755 * A339269 A013417 A013418

Adjacent sequences: A012449 A012450 A012451 * A012453 A012454 A012455

Keyword

sign

Author

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

Status

approved