1+2+...+n=n(n+1)/21^2+2^2+…+n^2=n(n+1)(2n+1)/61^3+2^3+…+n^3=n^2 * (n+1)^2 / 4明确这三个式子就好了.
1/4*n*(n+1)(n+2)(n+3)
