The series is  .

Find the convergence of the series by Ratio test.

Ratio Test :

(i) If , then the series is  is absolutely convergent.

(ii) If  or , then the series is  is divergent.

(iii) If , then the ratio test is inconclusive.

Here .

.

Find .

Series is convergent for all values of .

Series is convergent for all values of .