Find all x for which

$\displaystyle \displaystyle\sum\limits_{n=1}^\infty n^nx^n$

Attempt: Ratio Test

$\displaystyle \lim_{x \to +\infty} |\frac {(n+1)^{n+1}x^{n+1}}{n^nx^n}|$

$\displaystyle =(\frac{n+1}{n})^n(n+1)|x|$

$\displaystyle =(1+\frac{1}{n})^n(n+1)|x|$

$\displaystyle =e(n+1)|x|$

Where do I go from here?