If Σ_k =1^n a_k =6 n^3, then Σ_k =1^6((a_k +1 - a_k)/36)^2 is equal to ____.

If $\displaystyle \sum_{\mathrm{k}=1}^{\mathrm{n}} \mathrm{a}_{\mathrm{k}}=6 \mathrm{n}^3$, then $\displaystyle \sum_{\mathrm{k}=1}^6\left(\frac{\mathrm{a}_{\mathrm{k}+1}-\mathrm{a}_{\mathrm{k}}}{36}\right)^2$ is equal to $\displaystyle \_\_\_\_$.