MCS 401 homework #4 Due date: 19980928 D. J. Bernstein 19980921 Exercise 13. Baase 2.20. Count comparisons for (1) the top-down heap sort shown in the book and (2) the bottom-up heap sort shown in class. Exercise 14. Baase 2.25(a). Give an exact formula for all positive integers n. Exercise 15. Baase 2.25(b). Assume that there are exactly 10 keys. Exercise 16. Give a simple formula for 1 + 4x + 9x^{2} + 16x^{3} + ⋯ + n^{2}x^{n−1}. Check your answer for n = 3.