// x |x | \
|| ----------- for |--| < 1|
|| / x \ |n3| |
|| n3*|1 - --| |
|| \ n3/ |
|| |
n3*|< oo |
|| ___ |
|| \ ` |
|| \ -n n |
|| / n3 *x otherwise |
|| /__, |
\\n = 1 /
---------------------------------
x
$$\frac{n_{3} \left(\begin{cases} \frac{x}{n_{3} \left(1 - \frac{x}{n_{3}}\right)} & \text{for}\: \left|{\frac{x}{n_{3}}}\right| < 1 \\\sum_{n=1}^{\infty} n_{3}^{- n} x^{n} & \text{otherwise} \end{cases}\right)}{x}$$
n3*Piecewise((x/(n3*(1 - x/n3)), |x/n3| < 1), (Sum(n3^(-n)*x^n, (n, 1, oo)), True))/x