http://programmingpraxis.com/2011/11/15/phil-harveys-puzzle/

ph.clj

(defn combination [k xs]
  (if (pos? k)
    (if (<= (count xs) k) (list xs)
        (concat
         (map #(conj % (first xs)) (combination (dec k) (rest xs)))
         (combination k (rest xs))))))

(defn all-partitions [xs]
  (map #(list % (seq (reduce disj (set xs) %)))
       (combination (/ (count xs) 2) xs)))

(defn sum [xs] (apply + xs))

(defn sumofsquare [xs] (apply + (map #(* % %) xs)))

(defn sumofcube [xs] (apply + (map #(* % % %) xs)))

(defn phil-harvey
  "Phil Harvey wants us to partition {1,…,16} into two sets of
   equal size so each subset has the same sum, sum of squares
   and sum of cubes."
  [xs]
  (first (drop-while #(or (not= (sum (first %)) (sum (second %)))
                          (not= (sumofsquare (first %)) (sumofsquare (second %)))
                          (not= (sumofcube (first %)) (sumofcube (second %))))
                     (all-partitions xs))))