If f(x)=∑n=0∞cnxnf(x) = \sum_{n=0}^{\infty} c_n x^nf(x)=∑n=0∞cnxn has radius of convergence RRR, what is the radius of convergence of f(x3)f(x^3)f(x3)?
RRR
R3\sqrt[3]{R}3R
3R3R3R
R/3R/3R/3