\[{\mathrm{e}}^{-x}L^{(\alpha)}_{n}\left(x\right)=\int_{x}^{\infty}{\mathrm{e}}^%
{-y}L^{(\alpha+\mu)}_{n}\left(y\right)\frac{(y-x)^{\mu-1}}{\Gamma\left(\mu%
\right)}\,\mathrm{d}y,\]