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A009373 Expansion of log(1+tan(x))/cosh(x). 0
0, 1, -1, 1, -8, 65, -361, 2497, -23848, 256385, -2904601, 36778113, -520366208, 8014148545, -132884846641, 2373343120449, -45463597872688, 928532354406145, -20134914035881681, 462226423647925505, -11199802803793004888 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

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

FORMULA

a(n) ~ (n-1)! * (-1)^(n+1) * (4/Pi)^n / cosh(Pi/4). - Vaclav Kotesovec, Jan 23 2015

MATHEMATICA

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

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

CROSSREFS

Sequence in context: A316205 A305772 A317121 * A305589 A317007 A293802

Adjacent sequences:  A009370 A009371 A009372 * A009374 A009375 A009376

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 July 1 06:40 EDT 2022. Contains 354952 sequences. (Running on oeis4.)