A009423 Expansion of log(1+x)*log(1+tanh(x)).

0, 0, 2, -6, 14, -40, 204, -1316, 8728, -65472, 587520, -5909024, 63996096, -755614080, 9771577984, -136347987712, 2032096826880, -32315254874112, 547193693896704, -9816654494863360, 185846783267553280, -3704632705419493376

Offset

0,3

Links

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

Formula

a(n) ~ (n-1)! * (-1)^n * log((1+exp(2))/2). - Vaclav Kotesovec, Jan 23 2015

Mathematica

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

Crossrefs

Sequence in context: A271895 A151538 A284998 * A008325 A004066 A123383

Adjacent sequences: A009420 A009421 A009422 * A009424 A009425 A009426

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved