We work on $\mathbb{R}^n$ for a natural integer $n \geqslant 3$. We admit that the Dirichlet problem on the unit ball of $\mathbb{R}^n$, associated with a continuous function defined on the unit sphere $S_n(0,1)$, admits a unique solution. Let $m \in \mathbb{N}^*$.
Determine the dimension of $\mathcal{H}_m$ as a function of $m$ and $n$.