Chứng minh rằng: 122+132+142+152+...+120202

Chứng minh rằng:
              $\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+...+\frac{1}{{2020}^2}<\frac{2}{3}$