// -z |z| \
|| ---------- for --- < 1|
|| 2 2 |
|| / z\ |
|| 2*|1 + -| |
|| \ 2/ |
|| |
-z*|< oo |
|| ___ |
|| \ ` |
|| \ n -n n |
|| / n*(-1) *2 *z otherwise |
|| /__, |
||n = 0 |
\\ /
----------------------------------------
2
$$- \frac{z \left(\begin{cases} - \frac{z}{2 \left(\frac{z}{2} + 1\right)^{2}} & \text{for}\: \frac{\left|{z}\right|}{2} < 1 \\\sum_{n=0}^{\infty} \left(-1\right)^{n} 2^{- n} n z^{n} & \text{otherwise} \end{cases}\right)}{2}$$
-z*Piecewise((-z/(2*(1 + z/2)^2), |z|/2 < 1), (Sum(n*(-1)^n*2^(-n)*z^n, (n, 0, oo)), True))/2