Which series is ∑n=0∞x2n2n\sum_{n=0}^{\infty} \frac{x^{2n}}{2^n}∑n=0∞2nx2n?
11−x2/2\frac{1}{1-x^2/2}1−x2/21
11−x/2\frac{1}{1-x/2}1−x/21
11−2x2\frac{1}{1-2x^2}1−2x21
None of the above