Data Structures, Algorithms, & Applications in C++
Chapter 15, Exercise 9

In the induction base we show Nh = Fh+2 - 1 for h = 0 and 1. When h = 0, the left side is N0 = 0 and the right side is F2 - 1 = 1 - 1 = 0. When h = 1, the left side is N1 = 1 and the right side is F3 - 1 = 2 - 1 = 1.

For the induction hypothesis, assume that Nh = Fh+2 - 1 for h < m where m is an arbitrary integer > 1.

In the induction step, we must show that Nh = Fh+2 - 1 for h = m. The left side is Nm = Nm-1 + Nm-2 + 1. From the induction hypothesis, we obtain Nm-1 = Fm+1 - 1 and Nm-2 = Fm - 1. Therefore, Nm = Fm+1 - 1 + Fm - 1 + 1 = Fm+2 + 1.