counts the total weight of all n-walks (open and closed) on Cr . Our goal is to show that (5) counts the total number of all closed n-walks on Cr . Since each closed walk has weight 1, it suffices to show that the total weight of all open walks is zero. Consider an open walk X0 that begins at vertex 0 and ends at vertex m = 0. Then X0 generates the orbit {X0, X1, . . . , Xr−1} where walk X j starts at vertex j , and then follows the same forward and stationary instructions as X0, ending at vertex j + m (mod r ), with weight ωjm. Summing a finite geometric series, the total weight of the n-walks in this orbit is