Question

Kinda rusty on factorials
\[a_n = \frac{n!}{2^n} = \frac 1 2 \frac 2 2 \frac 3 2 ........\frac{(n-1)}{2}* \frac{n}{2}>= \frac 1 2 \frac n 2 = \frac n 4 \rightarrow \infty\]