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A009433 Expansion of log(1+x)/cosh(tan(x)). 0
0, 1, -1, -1, 0, -11, 15, 27, -504, 11817, -94185, 1226455, -12442056, 155936221, -1995562569, 27870901107, -423463160400, 6793396567633, -117302680146033, 2130615128588591, -40960288523646320, 827190717641773765 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,6

LINKS

Table of n, a(n) for n=0..21.

FORMULA

a(n) ~ (n-1)! * (-1)^(n+1) / cosh(tan(1)). - Vaclav Kotesovec, Jan 23 2015

MATHEMATICA

Log[ 1+x ]/Cosh[ Tan[ x ] ]

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

CROSSREFS

Sequence in context: A214863 A094766 A009407 * A275242 A030099 A085597

Adjacent sequences:  A009430 A009431 A009432 * A009434 A009435 A009436

KEYWORD

sign,easy

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

STATUS

approved

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Last modified May 26 09:42 EDT 2019. Contains 323579 sequences. (Running on oeis4.)