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.