Let f(x)=∑n=0∞anxnf(x) = \sum_{n=0}^{\infty} a_n x^nf(x)=∑n=0∞anxn have radius of convergence RRR. What is the radius of convergence of ∑n=0∞an2xn\sum_{n=0}^{\infty} a_n^2 x^n∑n=0∞an2xn?
RRR
R2R^2R2
R\sqrt{R}R
1/R1/R1/R