Discussion on: Daily Challenge #7 - Factorial Decomposition

(defn factors [n]
  (loop [res [], f 2, n n]
    (cond
      (= n 1)           res
      (zero? (rem n f)) (recur (conj res f) f (quot n f))
      :else             (recur res (inc f) n))))

(defn format-entry [[k v]]
  (apply str (if (= v 1) [k] [k \^ v])))

(defn decomp [n]
  (->> (range 2 (inc n))
       (mapcat factors)
       (reduce #(merge-with + %1 {%2 1}) (sorted-map))
       (map format-entry)
       (clojure.string/join " * ")))