Improve upon Exercise R13.6 by computing xn as (xn/2)2 if n is even. Why is this approach significantly faster? Hint: Compute x1023 and x1024 both ways.

Data from Exercise R13.6

Write a recursive definition of xn, where n ≥ 0, similar to the recursive definition of the Fibonacci numbers. Hint: How do you compute xn from xn – 1? How does the recursion terminate?