Let f(x)=∑n=0∞xn(n!)2f(x) = \sum_{n=0}^{\infty} \frac{x^n}{(n!)^2}f(x)=∑n=0∞(n!)2xn. What is the radius of convergence RRR?
R=1R = 1R=1
R=0R = 0R=0
R=eR = eR=e
R=∞R = \inftyR=∞