Its a general form of the combinations formula:
\begin{equation} {n \choose k_1, k_2, \dots, k_{n}} = \frac{n!}{k_{1}! k_2! \dots k_{n}!} \end{equation}
Its a general form of the combinations formula:
\begin{equation} {n \choose k_1, k_2, \dots, k_{n}} = \frac{n!}{k_{1}! k_2! \dots k_{n}!} \end{equation}