I am interested in studying the following recursion relation: $$i \tfrac{j(\ell-j+1)(n-j+1)(n+j+1)}{2(2j-1)(2j+1)} a_{j-1} - \tfrac {j(j+1)}2 a_j - i \tfrac{(j+1)(\ell+j+2)}2 a_{j+1} = \mu a_j,$$ with $n,\ell\in\mathbb{N}_0$ and $\mu\in\mathbb{R}$.

Does anybody know any famous family of polynomials on a finite discrete set solving this?

From already thank you very much.