Infinite Seriesmedium
0:00.0

Apply the Ratio Test to n=1n!4n(2n)!\sum_{n=1}^{\infty} \frac{n! \cdot 4^n}{(2n)!}. What is limnan+1an\lim_{n \to \infty} \left|\frac{a_{n+1}}{a_n}\right|?