数学公式

$\sum _{i=0}^n{i}^2=\frac{(n^2+n)(2n+1)}{6}$
$\sum _{i=0}^n{i}^2=\frac{(n^2+n)(2n+1)}{6}$
$\sum _{i=0}^n{i}^2=\frac{(n^2+n)(2n+1)}{6}$
$\sum _{i=0}^n{i}^2=\frac{(n^2+n)(2n+1)}{6}$
$\sum _{i=0}^n{i}^2=\frac{(n^2+n)(2n+1)}{6}$