The series is .
Consider the series .
.
It is geometric series with common ratio .
Geometric series with , is divergent.
Compare the series with
.
The Comparison Test:
\Suppose that and
are series with positive terms.
(i) If is convergent and
for all
, then
is also convergent.
(ii) If is divergent and
for all
, then
is also divergent.
Here .
Thus, by the comparision test series greater than the diverging series is also divergent.
\Therefore is divergent by part (ii) of the comparison Test.
is divergent.