A012619 cosh(arcsinh(x)*tan(x))=1+12/4!*x^4+120/6!*x^6+8400/8!*x^8...

1, 0, 12, 120, 8400, 237120, 41126976, 1414288512, 774359589120, -7305842952192, 43904341686828032, -6519096982922602496, 6522454342040400908288, -2519478812073315269099520

Offset

0,3

Links

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

Formula

a(n) ~ (-1)^n * sinh(Pi*tanh(1)/2) * tanh(1) * 2^(2*n) * n^(2*n-1) / exp(2*n). - Vaclav Kotesovec, Nov 01 2013

Mathematica

Table[n!*SeriesCoefficient[Cosh[ArcSinh[x]*Tan[x]], {x, 0, n}], {n, 0, 40, 2}] (* Vaclav Kotesovec, Nov 01 2013 *)
With[{nn=30}, Take[CoefficientList[Series[Cosh[ArcSinh[x]Tan[x]], {x, 0, nn}], x] Range[ 0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Dec 20 2021 *)

Crossrefs

Sequence in context: A012559 A009164 A012436 * A012563 A301898 A012441

Adjacent sequences: A012616 A012617 A012618 * A012620 A012621 A012622

Keyword

sign

Author

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

Status

approved