Euler31

e31.clj

(def denoms [200 100 50 20 10 5 2 1])
(def c (count denoms))

(defn calc
  "Return count for combinations, starting at the index for a given size denomination"
  [ndx value]
  (if (zero? value)
    1
    (->> (range ndx c)
       (map (fn [n] [n (- value (denoms n))]))
       (drop-while #(> 0 (second %)))
       (map #(apply calc %))
       (apply +))))