A009320 Expansion of log(1+log(1+x)*cosh(x)).

0, 1, -2, 10, -53, 373, -3289, 34543, -421994, 5884933, -92255061, 1606210571, -30754222080, 642299748231, -14531152719875, 354020726656465, -9240813172692064, 257285058656341145, -7611049992188970105

Offset

0,3

Links

Table of n, a(n) for n=0..18.

Formula

a(n) ~ (n-1)! * (-1)^(n+1) / (1-exp(-r))^n, where r = 0.8549045967031373719104055170906807819800761165... is the root of the equation 2*exp(-1 + exp(-r)) - r - exp(2/exp(r)-2)*r = 0. - Vaclav Kotesovec, Jan 24 2015

Mathematica

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

Crossrefs

Sequence in context: A221610 A247102 A370390 * A204186 A009322 A192697

Adjacent sequences: A009317 A009318 A009319 * A009321 A009322 A009323

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved