A012617 E.g.f.: tanh(arcsinh(x)*tan(x)) = 2/2!*x^2+4/4!*x^4-130/6!*x^6-6232/8!*x^8...

2, 4, -130, -6232, -32102, 18014060, 2634330582, -33133771824, -37925465839182, -16267772522154668, 2012491810909723310, 52146402203293345912, 867090565519403243923786, -388470254962420081890970180, 207203200777273698360429465094

Offset

1,1

Links

Alois P. Heinz, Table of n, a(n) for n = 1..100

Formula

a(n) ~ (-1)^(n+1) * sinh(1) * 2^(2*n+2) * n^(2*n-1) / (exp(2*n) * (cosh(Pi*tanh(1)+1) + cosh(Pi*tanh(1)-1) + 2*cosh(1))). - Vaclav Kotesovec, Oct 30 2013

Maple

a:= n-> (2*n)! *coeff(series(tanh(arcsinh(x)*tan(x)), x, 2*n+2), x, 2*n):
seq (a(n), n=1..20);  # Alois P. Heinz, Jul 11 2012

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Tanh[ArcSinh[x]Tan[x]], {x, 0, nn}], x] Range[0, nn]!, {3, -1, 2}]] (* Harvey P. Dale, Jul 11 2012 *)

Crossrefs

Sequence in context: A369699 A012561 A012558 * A012614 A018500 A353790

Adjacent sequences: A012614 A012615 A012616 * A012618 A012619 A012620

Keyword

sign

Author

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

Extensions

Definition clarified by and more terms from Harvey P. Dale, Jul 11 2012

Status

approved