An ordered partition of $[n]$ is a $k$-tuple $(A_1, A_2, . . . , A_k)$ of distinct sets for which the set $\{A_1, A_2, . . . , A_k\}$ is a partition of $[n]$. Thus, each set $A_i$ is nonempty and each partition of $n$ into $k$ blocks gives rise to $k!$ ordered partitions of $[n]$. (For positive integers $n$, the number $k$ can vary from $1$ to $n$.) Find a simple expression for the exponential generating function in which the coefficient of $\frac{x^n}{n!}$ is the number of ordered partitions of $[n]$.
I have no idea how to start this problem, any help would be great! Thank you