Infinite Serieseasy
0:00.0

Apply the ratio test to n=1n!3n(2n)!\sum_{n=1}^{\infty} \frac{n! \cdot 3^n}{(2n)!} Compute limnan+1an\lim_{n \to \infty} \left|\frac{a_{n+1}}{a_n}\right| and determine convergence.