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A009396 Expansion of log(1+tanh(x)*sin(x)). 1
0, 2, -24, 742, -46424, 4924442, -795624324, 182148217942, -56122289514224, 22395847873848242, -11236967462922272124, 6923916000862956967342, -5139905036702596261514024, 4524378924970721231979687242 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

FORMULA

a(n) ~ (2*n)! * (-1)^(n+1) / (n * r^(2*n)), where r = 0.82560766907116185156994603327818731... is the root of the equation cos(r) = tanh(r). - Vaclav Kotesovec, Jan 23 2015

MATHEMATICA

Log[ 1+Tanh[ x ]*Sin[ x ] ] (* Even Part *)

nn = 20; Table[(CoefficientList[Series[Log[1 + Sin[x]*Tanh[x]], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* Vaclav Kotesovec, Jan 23 2015 *)

CROSSREFS

Sequence in context: A012161 A009724 A177771 * A338188 A274634 A292694

Adjacent sequences:  A009393 A009394 A009395 * A009397 A009398 A009399

KEYWORD

sign

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

STATUS

approved

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Last modified December 9 09:37 EST 2021. Contains 349627 sequences. (Running on oeis4.)