(define fermat-number ; computes the nth
(lambda (n) ; Fermat number
(+ (repeatedly-square 2 n) 1)))
> (fermat-number 0)
3
> (fermat-number 1)
5
> (fermat-number 2)
17
> (fermat-number 3)
257
> (fermat-number 4)
65537
> (fermat-number 5)
4294967297
> (fermat-number 6)
18446744073709551617
Since Fermat numbers are starting to get too large to comprehend, we will
consider the number of digits in them.