euler-3.clj

(defn prob3 [target]
  (let [factorials [] biggest target]
    (dotimes [num target]

      (if-not (or (contains? [0, 1] num) (> num biggest))
        (if (= (rem target num) 0)
          (recur [(/ biggest num)
                  (if-not (contains? factorials num)
                   (def factorials (conj factorials num)))
                 ]))))
    (println factorials)))

(time (p3 600851475143))