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.

The series is .

.

If then .

.

Since , then the series is  is inconclusive.

But, , so the series diverges.

Therefore, the series diverges by ratio test.

Series is diverges.