// / / ___\\ \
|| 2 |15/2 - 5*x (-15 + 15*x)*atanh\\/ x /| |
||x *|---------- + -------------------------| |
|| | 2 5/2 | |
|| \ x 2*x / |
||------------------------------------------- for |x| <= 1|
|| 15 |
|| |
|| oo |
x*|< ____ |
|| \ ` |
|| \ n |
|| \ x |
|| ) --------- otherwise |
|| / 2 |
|| / -1 + 4*n |
|| /___, |
|| n = 2 |
\\ /
$$x \left(\begin{cases} \frac{x^{2} \left(\frac{\frac{15}{2} - 5 x}{x^{2}} + \frac{\left(15 x - 15\right) \operatorname{atanh}{\left(\sqrt{x} \right)}}{2 x^{\frac{5}{2}}}\right)}{15} & \text{for}\: \left|{x}\right| \leq 1 \\\sum_{n=2}^{\infty} \frac{x^{n}}{4 n^{2} - 1} & \text{otherwise} \end{cases}\right)$$
x*Piecewise((x^2*((15/2 - 5*x)/x^2 + (-15 + 15*x)*atanh(sqrt(x))/(2*x^(5/2)))/15, |x| <= 1), (Sum(x^n/(-1 + 4*n^2), (n, 2, oo)), True))