Faber F2
From specialfunctionswiki
The Faber function $F_2$ is defined by $$F_2(x)=\displaystyle\sum_{k=1}^{\infty} \dfrac{1}{k!} \displaystyle\inf_{m \in \mathbb{Z}} \left|2^{k!}x-m \right|.$$
Graph of $F_2$.
Properties
Faber F2 is continuous
Faber F2 is nowhere differentiable
