I need to describe:
$${n \choose k,0,l,0,m}$$
as three rising factorials. How can I do this?
As far as I know I can delete zero's, so it would be:
$${n \choose k,l,m}=\frac{n!}{k!l!m!},$$
where $k+l+m=n$.
Rising factorial can be written as:
$$\frac{(n+k-1)!}{(n-1)!}$$
But what's next?
Provided $k+l+m=n$, the multinomial coefficient satisfies \begin{align*} \binom{n}{k,l,m} &= \binom{n}{k}\binom{n-k}{l}\binom{n-k-l}{m} \\ &= \frac{1}{k!} (n-k+1)^{(k)} \times \frac{1}{l!} (n-k-l+1)^{(l)} \times \frac{1}{m!} (n-k-l-m+1)^{(m)}. \end{align*}
Could this be what you're after?