Evaluate a pile of cubes

pileOfCubes.clj

;; Link to KATA: http://www.codewars.com/kata/5592e3bd57b64d00f3000047/train/clojure

;; Your task is to construct a building which will be a pile of n cubes. The cube at the bottom will have a volume of n^3, the cube above will have volume of (n-1)^3 and so on until the top which will have a volume of 1^3.

;; You are given the total volume m of the building. Being given m can you find the number n of cubes you will have to build?

;; The parameter of the function findNb (find_nb, find-nb) will be an integer m and you have to return the integer n such as n^3 + (n-1)^3 + ... + 1^3 = m if such a n exists or -1 if there is no such n.

;; EXAMPLES
;; findNb(1071225) --> 45
;; findNb(91716553919377) --> -1

;; BREAKS ON: expected: (= (find-nb 10252519345963644753026N) -1) - actual: (not (= 450010 -1))

;; My Solution
(defn find-nb [goal]
  (loop [n 0]
    (cond
      (= (double (+' (*' n n) n)) (*' (Math/sqrt goal) 2))
        n
      (> (+' (*' n n) n) (*' (Math/sqrt goal) 2))
        -1
      :else
        (recur (+ n 1))
    )
  )
)