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A012587 E.g.f.: tan(arcsinh(x)*exp(x))=x+2/2!*x^2+4/3!*x^3+24/4!*x^4+180/5!*x^5... 0
0, 1, 2, 4, 24, 180, 1240, 10456, 112896, 1316816, 16378528, 229634304, 3569726336, 59315089600, 1055150016128, 20254767489152, 415619313491968, 9028238025838848, 207506148418183680, 5043727679716764672 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..19.

FORMULA

a(n) ~ n! / ((Pi/2 + exp(r)/sqrt(1+r^2)) * r^(n+1)), where r = 0.782048434734397136830260131892318660005898990290325... is the root of the equation arcsinh(r)*exp(r) = Pi/2. - Vaclav Kotesovec, Feb 06 2015

MATHEMATICA

With[{nn=20}, Join[{0}, Rest[CoefficientList[Series[Tan[ArcSinh[x]Exp[x]], {x, 0, nn}], x]Range[0, nn]!]]] (* Harvey P. Dale, May 07 2012 *)

CROSSREFS

Sequence in context: A275553 A009672 A018988 * A012292 A211934 A012592

Adjacent sequences:  A012584 A012585 A012586 * A012588 A012589 A012590

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified September 23 10:47 EDT 2020. Contains 337298 sequences. (Running on oeis4.)