study the convergence of the following series indicating the radius of convergence and the interval of convergence

i) $\displaystyle

\sum\limits_{n = 1}^\infty {sen\left( {\pi \left( {n + \frac{1}{n}} \right)} \right)} x^n

$

ii)$\displaystyle

\sum\limits_{n = 1}^\infty {\ln \left( {1 + \frac{1}{{n^2 }}} \right)} x^n

$

please i need help with this to understand how to do it D: