Assuming the series is

The series will converge if

We have

So the series will certainly converge if

, but we also need to check the endpoints of the interval.
If

, then the series is a scaled harmonic series, which we know diverges.
On the other hand, if

, by the alternating series test we can show that the series converges, since

and is strictly decreasing.
So, the interval of convergence for the series is

.