연습문제 1.27

(define (full-fermat-test n)
  (define (iter a)
    (cond ((= a 1) #t)
          ((= (expmod a n n ) a) (iter (- a 1)))
          (else #f)))
  (iter (- n 1)))

> (full-fermat-test 561)
#t
/> (full-fermat-test 1105)
#t
/> (full-fermat-test 1729)
#t
/> (full-fermat-test 2465)
#t
/> (full-fermat-test 2821)
#t
/> (full-fermat-test 6601)
#t