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