// -3 |x| \ // 3 |x| \
|| --- for --- < 1| || - for --- < 1|
|| x 3 | || x 3 |
|| | || |
|| oo | || oo |
|< ___ | + |< ___ |
|| \ ` | || \ ` |
|| \ -n n | || \ -n 2 n |
|| / n*3 *x otherwise | || / 3 *n *x otherwise |
|| /__, | || /__, |
\\n = -1 / \\n = -1 /
$$\begin{cases} - \frac{3}{x} & \text{for}\: \frac{\left|{x}\right|}{3} < 1 \\\sum_{n=-1}^{\infty} 3^{- n} n x^{n} & \text{otherwise} \end{cases} + \begin{cases} \frac{3}{x} & \text{for}\: \frac{\left|{x}\right|}{3} < 1 \\\sum_{n=-1}^{\infty} 3^{- n} n^{2} x^{n} & \text{otherwise} \end{cases}$$
Piecewise((-3/x, |x|/3 < 1), (Sum(n*3^(-n)*x^n, (n, -1, oo)), True)) + Piecewise((3/x, |x|/3 < 1), (Sum(3^(-n)*n^2*x^n, (n, -1, oo)), True))