%I #16 Apr 11 2017 02:50:15
%S 0,1,-1,4,-18,106,-750,6196,-58408,617716,-7234020,92842696,
%T -1294948776,19493497024,-314874396928,5430592728016,-99578626460160,
%U 1934092698170896,-39660351268817808,856128235903319296
%N Expansion of sinh(sinh(log(1+x))).
%H G. C. Greubel, <a href="/A009597/b009597.txt">Table of n, a(n) for n = 0..440</a>
%F a(n) ~ n! * (-1)^(n+1) * exp(1/4 + sqrt(2*n)) / (2^(9/4) * n^(3/4) * sqrt(Pi)). - _Vaclav Kotesovec_, Jan 24 2015
%t Sinh[ Sinh[ Log[ 1+x ] ] ]
%t CoefficientList[Series[Sinh[(x*(2 + x))/(2*(1 + x))], {x, 0, 20}], x] * Range[0, 20]! (* _Vaclav Kotesovec_, Jan 24 2015 *)
%o (PARI) x='x+O('x^50); concat([0], Vec(serlaplace(sinh(sinh(log(1+x)))))) \\ _G. C. Greubel_, Apr 11 2017
%K sign,easy
%O 0,4
%A _R. H. Hardin_
%E Extended with signs by _Olivier GĂ©rard_, Mar 15 1997