(defn square [n]
  (* n n))

(defn divides? [a b]
  (= (mod b a) 0))

(defn smallest-divisor [n]
  (defn iter [n test]
    (cond
      (> (square test) n) n
      (divides? test n) test
      (iter n (+ test 1))))
  (iter n 2))

(defn prime? [n]
  (= n (smallest-divisor n)))

(defn search-for-primes [start count]
  (defn report-time [n elapsed-time]
    (printf "%d *** %fus" n (* elapsed-time 1000000.0)))
  (defn start-prime-test [n start-time]
    (if (prime? n)
      (do
        (report-time n (- (os/clock :cputime) start-time))
        true)
      false))
  (defn times-prime-test [n]
    (start-prime-test n (os/clock :cputime)))
  (defn iter [test n]
    (cond
      (= n 0) 0
      (times-prime-test test) (iter (+ test 2) (- n 1))
      (iter (+ test 2) n)))
  (cond
    (= 0 (mod start 2)) (iter (+ start 1) count)
    (iter start count)))

(search-for-primes 1000 3)
(search-for-primes 10000 3)
(search-for-primes 100000 3)
(search-for-primes 1000000 3)
(search-for-primes 10000000 3)
(search-for-primes 100000000 3)