What is the meaning of adding $k$, and $1$, to $n$ in $\frac{(n+k-1)!}{{k!}{(n-1)!}}$, $C^i_{n,k}$, and how to visualise the components of this formula?
Here is my research:
What is the meaning of adding $k$, and $1$, to $n$ in $\frac{(n+k-1)!}{{k!}{(n-1)!}}$, $C^i_{n,k}$, and how to visualise the components of this formula?
Here is my research: