I have to prove the serial representation of: \begin{equation*} \int^1_0 x^x\,{\rm d}x=\sum^{\infty}_{n=0}\frac{(-1)^{n-1}}{n^n}. \end{equation*}
It obtains: \begin{equation*} x^x=\sum^{\infty}_{n=0}\frac{(f(x))^n}{n!}. \end{equation*}
The function $f(x)$ is continuous in $[0,1]$.