Page 441, Exercise 4

Induction Base:  The finding is true for a tree of degree 0 since 2⁰=1.  A tree of degree 1 has 2⁰·2= 2 nodes. Induction Hypothesis: For all 1 < i < n, the number of nodes = 2^n-1·2.
Induction Step:  The number of nodes in a tree of degree n is 2ⁿ = 2^n-1·n, which is obviously true.