// 1 1 \
||------------------- for -------- < 1|
|| ____ / 1 \ | ____| |
||\/ n2 *|1 - ------| |\/ n2 | |
|| | ____| |
|| \ \/ n2 / |
|| |
|| oo |
oo + |< ____ |
|| \ ` |
|| \ -n |
|| \ --- |
|| / 2 otherwise |
|| / n2 |
|| /___, |
|| n = 1 |
\\ /
$$\begin{cases} \frac{1}{\sqrt{n_{2}} \left(1 - \frac{1}{\sqrt{n_{2}}}\right)} & \text{for}\: \frac{1}{\left|{\sqrt{n_{2}}}\right|} < 1 \\\sum_{n=1}^{\infty} n_{2}^{- \frac{n}{2}} & \text{otherwise} \end{cases} + \infty$$
oo + Piecewise((1/(sqrt(n2)*(1 - 1/sqrt(n2))), 1/Abs(sqrt(n2)) < 1), (Sum(n2^(-n/2), (n, 1, oo)), True))