In the general model of a Pólya urn ($b = c = 0$, $a = d$), using the results established so far (in particular that $H = G$ on $D_{\rho}$), conclude that, for all integers $n$ and for all $k \in \llbracket 0, n \rrbracket$,
$$P(X_{n} = a_{0} + ka) = \binom{n}{k} \frac{L_{k}(a_{0}/a) L_{n-k}(b_{0}/a)}{L_{n}(a_{0}/a + b_{0}/a)}$$