Formula_3483

\[f_{n}\left(\varepsilon_{1}, \varepsilon_{2}, \ldots, \varepsilon_{n} ; t\right)=\frac{\partial^{n}}{\partial \varepsilon_{1} \partial \varepsilon_{2} \ldots \partial \varepsilon_{n}} \mathrm{E}\left[\xi\left(t, \varepsilon_{1}\right) \ldots \xi\left(t, \varepsilon_{n}\right)\right] .\]