# Math Help - annulus of convergence

1. ## annulus of convergence

calculate the annulus of convergence of $\Sigma _{j=-\infty, j \neq 0} ^\infty z^j / j^j$

2. The critical point is relative to the sum of the powers of z with negative exponent...

$\sum_{j=1}^{\infty} \frac{(-j)^{j}}{z^{j}}$ (1)

In fact the (1) diverges for any value of $z\ne 0$...

Kind regards

$\chi$ $\sigma$