Cannot understand a solution to evaluating $C_{2}^{2000}+C_{5}^{2000}+C_{8}^{2000}+\cdots+C_{2000}^{2000}$
Find the value of $\binom{2000}{2} + \binom{2000}{5} + \binom{2000}{8} + \cdots \binom{2000}{2000}$