\[a_{n}=\frac{e^{-z/2}}{z^{n-\kappa}n!}\left(\mu^{2}-(\kappa-\tfrac{1}{2})^{2}%
\right)\*\left(\mu^{2}-(\kappa-\tfrac{3}{2})^{2}\right)\*\cdot\cdot\cdot\left(%
\mu^{2}-(\kappa-n+\tfrac{1}{2})^{2}\right).\]