Excel A1 Converter 2

NtoA1-2.clj

(defn N->A [n]
  (let [za "0ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        alen (dec (count za))
        iter (fn [[n xs]] [(int (/ n alen))
                           (cons (nth za (rem n alen)), xs)])]
    (->> (iterate iter [n '()])
         (drop-while (comp not zero? first))
         first second
         (apply str))))


(N->A 10000000000) ;=> "AFIPYQJP"