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A012613 tan(arcsinh(x)*tan(x))=2/2!*x^2+4/4!*x^4+350/6!*x^6+7208/8!*x^8... 0
0, 2, 4, 350, 7208, 1278298, 79874540, 24248146806, 3094746649296, 1450703467495218, 311518889830786132, 210537148539150077966, 67821849231894539132920, 62959878878133692157576586 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

FORMULA

a(n) ~ (-1)^(n+1) * tanh(1) * 2^(2*n+1) * n^(2*n-1) / (exp(2*n) * (1+cos(Pi*tanh(1)))). - Vaclav Kotesovec, Oct 31 2013

MATHEMATICA

Table[n!*SeriesCoefficient[Tan[ArcSinh[x]*Tan[x]], {x, 0, n}], {n, 0, 40, 2}] (* Vaclav Kotesovec, Oct 31 2013 *)

CROSSREFS

Sequence in context: A012368 A009705 A012372 * A012618 A012557 A012562

Adjacent sequences: A012610 A012611 A012612 * A012614 A012615 A012616

KEYWORD

nonn

AUTHOR

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

EXTENSIONS

Prepended missing a(0)=0 from Vaclav Kotesovec, Oct 31 2013

STATUS

approved

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Last modified February 8 09:30 EST 2023. Contains 360138 sequences. (Running on oeis4.)