Given f(x)=∑n=0∞cnxnf(x) = \sum_{n=0}^{\infty} c_n x^nf(x)=∑n=0∞cnxn with cn=nn2+1c_n = \frac{n}{n^2+1}cn=n2+1n, find the radius of convergence RRR.
R=0R = 0R=0
R=1R = 1R=1
R=eR = eR=e
R=∞R = \inftyR=∞