Permutations of multiset $\frac{n!}{p!q!r!}$ (n objects with duplicates: divide factorial by factorials of counts per)

jee-mainjee-advanced

n objects with duplicates: divide factorial by factorials of counts per type.

What each symbol means

SymbolWhat it stands for
n,p,q,rTotal and repetition multiplicities

When to use this

Objects partitioned into identical classes.