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