A009638 - OEIS

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A009638

Expansion of e.g.f.: tan(log(1+sinh(x))).

0, 1, -1, 5, -22, 151, -1186, 11255, -121752, 1493101, -20381896, 306816905, -5045231632, 89977880851, -1729461315856, 35637607318955, -783658693590912, 18315607922069401, -453368586519154816, 11848112075773043405

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OFFSET

0,4

LINKS

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

FORMULA

a(n) ~ n! * (-1)^(n+1) / (sqrt(1-2*exp(Pi/2)+2*exp(Pi)) * log(1 - exp(-Pi/2) + sqrt(1 + (exp(-Pi/2)-1)^2))^(n+1)). - Vaclav Kotesovec, Jan 23 2015

MATHEMATICA

CoefficientList[Series[Tan[Log[1 + Sinh[x]]], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 23 2015 *)

CROSSREFS

Sequence in context: A372139 A028561 A227918 * A346410 A121942 A006294

Adjacent sequences: A009635 A009636 A009637 * A009639 A009640 A009641

KEYWORD

sign,easy

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

First Mathematica program deleted and definition clarified by Harvey P. Dale, Feb 20 2023

STATUS

approved