This function calculate the multinomial coefficient
$$\frac{(\sum n_j)!}{\prod n_j!}.$$
where $n_j$'s are the number of multiplicities in the multiset.
Usage
multichoose(n)
Arguments
n
a vector of group sizes
Value
multinomial coefficient
Details
The result is not reliable if the retunred value is too large (around 2^53) due to limition of integers.