If $$y=1+\frac{x}{1 !}+\frac{x^2}{2 !}+\frac{x^3}{3 !} \ldots$$, then $$\frac{d y}{d x}$$ is equal to
The value of $$\frac{d}{d x}\left(x^n \log _a x e^x\right)$$ is