Faber F1
From specialfunctionswiki
The Faber functions are $$F_1(x)=\displaystyle\sum_{k=1}^{\infty} \dfrac{1}{10^k} \displaystyle\inf_{m \in \mathbb{Z}} \left|2^{k!} x -m \right|$$ and $$F_2(x)=\displaystyle\sum_{k=1}^{\infty} \dfrac{1}{k!} \displaystyle\int_{m \in \mathbb{Z}} \left|2^{k!}x-m \right|.$$
