Exercise 3 (7.30). We have used exponential generating functions to show that the number , of ways to color the squares of a 1-by-n board with the colors red, white, and blue, where the number of red squares is even and there is at least one blue square, satisfies the formula, for n > 1 302 - 272 + 1 hn 2 with ho = 0. Obtain an alternative derivation of this formula by finding a recurrence relation satisfied by hn and then solving the recurrence relation