Let $\alpha$ be a positive real number, and $n,m$ two positive integers.
Is there a closed form for this sum?
$$\sum_{k_1 + \cdots+k_m = n} \frac{\Gamma(k_1 + \alpha)}{k_1!} \ldots \frac{\Gamma(k_m + \alpha)}{k_m!}$$
where the sum goes through all nonnegative integers $k_i$ such that $\sum k_i = n$.