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A009647
Expansion of tan(log(1+x))/cosh(x).
0
0, 1, -1, 1, -12, 95, -615, 5003, -52192, 600029, -7464645, 102853749, -1558643724, 25565811531, -450966117147, 8528942156655, -172180452813600, 3693485934629625, -83891436038405865, 2011562464233339561
OFFSET
0,5
FORMULA
a(n) ~ n! * (-1)^(n+1) / ((exp(Pi/2)-1) * cosh(1-exp(-Pi/2)) * (1-exp(-Pi/2))^n). - Vaclav Kotesovec, Jan 23 2015
MATHEMATICA
Tan[ Log[ 1+x ] ]/Cosh[ x ]
CoefficientList[Series[Sech[x]*Tan[Log[1 + x]], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 23 2015 *)
CROSSREFS
Sequence in context: A045894 A045829 A220683 * A038836 A026860 A021074
KEYWORD
sign,easy
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
STATUS
approved