Let i=√ -1. If ((-1+i √ 3 )^21)/((1-i)^24)+((1+i √ 3 )^21)/((1+i)^24)=k, and n =[|k|] be the greatest integral part of |k|. Then Σ_j=0^n +5…

Let $\displaystyle i=\sqrt{-1}$. If $\displaystyle \frac{(-1+i \sqrt{3})^{21}}{(1-i)^{24}}+\frac{(1+i \sqrt{3})^{21}}{(1+i)^{24}}=k$, and $\displaystyle \mathrm{n}=[|k|]$ be the greatest integral part of $\displaystyle |k|$. Then $\displaystyle \sum_{j=0}^{\mathrm{n}+5}(j+5)^2-\sum_{j=0}^{\mathrm{n}+5}(j+5)$ is equal to \_\_\_\_.