(defn fibs
  ([]
     (fibs 0 nil nil))
  ([n val1 val2]
     (lazy-seq
      (let [val3 (condp = n 0 0, 1 1, (+ val1 val2))]
        (cons val3
            (fibs (inc n) val2 val3))))))

(defn fib
  [n]
  (->> (fibs)
      (drop n)
      first))