euler12.clj

(def triangle-numbers
         (lazy-cat [1]
                   (map + triangle-numbers (iterate inc 2))))
 
(defn num_devisors [x]
    (* 2 (count (filter #(= (rem x %) 0)
                        (range 1 (Math/sqrt x))))))
 
(first
       (filter #(> (num_devisors %) 500)
               triangle-numbers))