A012836 arcsinh(sec(x)*tanh(x))=x+20/5!*x^5-280/7!*x^7+18000/9!*x^9...

1, 0, 20, -280, 18000, -1277760, 159922880, -26119949440, 5923118588160, -1705199348152320, 619341836139299840, -274598298613483878400, 146431095418622106193920, -92305017354779154307399680

Offset

0,3

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[ArcSinh[Sec[x]Tanh[x]], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, May 10 2026 *)

Crossrefs

Sequence in context: A021474 A017999 A244653 * A028294 A278360 A019040

Adjacent sequences: A012833 A012834 A012835 * A012837 A012838 A012839

Keyword

sign

Author

Patrick Demichel

Status

approved