I have this doubt:
Given $n\in \mathbb{N}$, does exist $k\in \mathbb{N}$ such that $2^k$ contains $n$ as a string in it?
For example, $53$ is in $2^{16}=65\color{red}{53}6$.
I just thought the problem right now so I don't have knowledge if it's even possible to solve it, but sounds a very nice problem. Does someone has an idea?