Correct Answer!

By the :

Consider the series

¥
å
n = 1 
| an| = ¥
å
n = 1 
arctan(n)
n2+1
and compare it to the convergent p-series (p=2):

å
bn = ¥
å
n = 1 
1
n2
Since both series have positive terms and the limit

lim
x® ¥ 
|an|
bn
= p
2
is finite an positive then the implies convergence of the series.

Note that this problem can also be solved using the Integral Test and the Direct Comparison Test.