Palindromic Numbers

gistfile1.clj

(let [exp10 #(reduce * 1 (repeat % 10))  
      combine (fn [n1 ev]
                (loop [r n1 n2 (if ev n1 (quot n1 10))]
                  (if (zero? n2) r
                      (recur (+ (* 10 r) (rem n2 10)) (quot n2 10)))))
      gen (fn gen [start end ev]  
            (lazy-cat
             (if ev nil (map #(combine % ev) (range start end)))
             (map #(combine % true) (range (if ev start (quot end 10)) end))
             (gen end (* end 10) false)))
      source (lazy-cat [0] (gen 1 10 false))
      ]
  (fn [n]
    (if (< n 10) (drop-while #(< % n) source)
        (let [s (str n)  
              ev (even? (.length s))  
              hl (- (.length s) (int (/ (.length s) 2)))  
              h (read-string (.substring s 0 hl)) ]
          (drop-while #(< % n) (gen h (exp10 hl) ev))))))