$\displaystyle\sum_{n=1}^{\infty}\frac{(-1)^{n+1}x^n}{n}$, converges for $-1 < x \leq 1$

$\displaystyle\sum_{n=0}^{\infty}\frac{x^n}{n}$, converges for $|x|<1$

$\displaystyle\sum_{n=1}^{\infty}\frac{x^n}{n}$, converges for $-1 \leq x < 1$

$\displaystyle\sum_{n=1}^{\infty}\frac{(-1)^{n}x^n}{n}$, converges for $|x|\leq 1$