Recamán Sequence (A005132)
If you want a lazy sequence, this may be a good example of using Python-style generator functions.  An example:

(defn concat-gen    ; concat a list of collections
  [&amp; collections]
  (lazy-gen
    (doseq [curr-coll collections]
      (doseq [item curr-coll]
        (yield item)))))

(defn concat-gen-pair
  [&amp; collections]
  (lazy-gen
    (doseq [curr-coll collections]
      (doseq [item curr-coll]
        (yield-all [item item])))))

(def c1 [1 2 3])
(def c2 [4 5 6])
(def c3 [7 8 9])

(is= [1 2 3 4 5 6 7 8 9]                            (concat-gen       c1 c2 c3))
(is= [1 1  2 2  3 3  4 4  5 5  6 6  7 7  8 8  9 9]  (concat-gen-pair  c1 c2 c3))