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