Functional Programming: The Sums of Powers --> https://www.hackerrank.com/challenges/functional-programming-the-sums-of-powers

power-of-sum.clj

(defn nth-root
  [x n]
  (Math/pow Math/E (/ (Math/log x) n)))

(defn sum-of-powers
  [sum n start]
  (let [upper-bound (int (inc (nth-root sum n)))]
    (->> (range start (inc upper-bound))
         (map
          (fn [x]
            (let [remain (- sum (int (Math/pow x n)))]
              (cond (zero? remain) 1
                    (neg?  remain) 0
                    :else (sum-of-powers remain n (inc x))))))
         (reduce +))))

(sum-of-powers 100 3 1)