$\"\"$

The series $\"\"$ .

The value of $\"\"$ .

$\"\"$ , consider $\"\"$ .

By limit comparision test, $\"\"$ , the both $\"\"$ and $\"\"$ either convergence or divergence.

The series $\"\"$ is divergent by $\"\"$ -series test.

Therefore, $\"\"$ is also divergent.

$\"\"$

The series $\"\"$ is divergent.