Partial sums intro

The $n\text{th}$‍ partial sum of the series $\sum _{n=1}^{\mathrm{\infty }}{a}_n$‍ is given by

${\displaystyle S_n=6-\frac{3}{n^2}}$‍.

${\displaystyle \sum _{n=1}^9{a}_n=}$‍