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A012252 exp(arcsinh(arcsinh(x))) = 1+x+1/2!*x^2-1/3!*x^3-7/4!*x^4+9/5!*x^5... 0
1, 1, 1, -1, -7, 9, 169, -225, -8751, 11025, 789681, -893025, -110381943, 108056025, 22142611737, -18261468225, -6041067843807, 4108830350625, 2153812782224097, -1187451971330625, -972958293249140583 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

Table of n, a(n) for n=0..20.

FORMULA

a(n) ~ (-1)^(n/2+1) * 2 * sqrt(tan(1)) * n^(n-1) * exp(-n) / (sin(1))^n, if n is even and a(n) ~ (-1)^((n-1)/2) * 2 * n^(n-1)*exp(-n), if n is odd. - Vaclav Kotesovec, Oct 30 2013

MATHEMATICA

CoefficientList[Series[Exp[ArcSinh[ArcSinh[x]]], {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Oct 30 2013 *)

CROSSREFS

Sequence in context: A116237 A123746 A152551 * A262538 A306184 A027723

Adjacent sequences:  A012249 A012250 A012251 * A012253 A012254 A012255

KEYWORD

sign

AUTHOR

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

STATUS

approved

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Last modified September 23 20:42 EDT 2021. Contains 347617 sequences. (Running on oeis4.)