\[S(x)\sim\frac{2\pi}{\sqrt{3}}\sum_{s=0}^{\infty}(-1)^{s}{\genfrac{(}{)}{0.0pt}%
{}{-\frac{1}{3}}{s}}x^{-s-(1/3)}-\sum_{s=1}^{\infty}\frac{3^{s}(s-1)!}{2\cdot 5%
\cdots(3s-1)}x^{-s};\]