(fn [x] (let [digits (fn digits
                        [x] (->> x
                                 str
                                 vec
                                 (map #(str %))
                                 (map #(Integer/parseInt %))))
               squares (fn squares [x] (map #(* % %) (digits x)))
               sum-of-squares (fn sum-of-squares [x] (reduce + (squares x)))
               initial-value x]
           (loop [new-sum (sum-of-squares x)
                  old-numbers #{x}]
               (cond
                 (= 1 new-sum) true
                 (old-numbers new-sum) false
                 :else (recur (sum-of-squares new-sum) (conj old-numbers new-sum))))))