A009336 - OEIS

A009336

Expansion of log(1+sin(x))/cosh(x).

0, 1, -1, -2, 4, 20, -61, -296, 1184, 9680, -49201, -393120, 2361844, 26927680, -191422141, -2138039424, 17147588384, 250712561920, -2289437638081, -32881696158208, 329955144475204, 5885687604556800, -65643617893832221

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OFFSET

0,4

LINKS

Table of n, a(n) for n=0..22.

FORMULA

a(n) ~ n! * 2^(n+2) * (cos(Pi*n/2) * log(cosh(Pi/2)) + arctan(sinh(Pi/2)) * sin(Pi*n/2)) / Pi^(n+1). - Vaclav Kotesovec, Jan 24 2015

MATHEMATICA

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

CoefficientList[Series[Log[1 + Sin[x]]*Sech[x], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 24 2015 *)

CROSSREFS

Sequence in context: A027741 A137697 A192380 * A274520 A337616 A238229

Adjacent sequences: A009333 A009334 A009335 * A009337 A009338 A009339

KEYWORD

sign,easy

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

STATUS

approved