A012551 arctanh(sinh(x)*tan(x))=2/2!*x^2+12/4!*x^4+382/6!*x^6+23352/8!*x^8...

2, 12, 382, 23352, 2464922, 398069892, 91079960662, 28062488827632, 11197997254599602, 5618500857338248572, 3461960315033768973742, 2569953015248391982844712, 2262189595338137069466955082

Offset

0,1

Links

Table of n, a(n) for n=0..12.

Formula

a(n) ~ (2*n+1)! / r^(2*n+2), where r = 0.825607669071161851569946... is the real root of the equation tan(r)*sinh(r)=1. - Vaclav Kotesovec, Oct 24 2013

Mathematica

Table[n!*SeriesCoefficient[ArcTanh[Sinh[x]*Tan[x]], {x, 0, n}], {n, 2, 40, 2}] (* Vaclav Kotesovec, Oct 24 2013 *)

Crossrefs

Sequence in context: A266241 A012547 A009706 * A156509 A229919 A287679

Adjacent sequences: A012548 A012549 A012550 * A012552 A012553 A012554

Keyword

nonn

Author

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

Status

approved