methylene

;; A version of the ackermann function, described in https://u.osu.edu/friedman.8/files/2014/01/LongFinSeq98-2f0wmq3.pdf

(require '[clojure.core.match :refer [match]])

(defn ackermann [[k & r :as s] n]
  (if (not (seq s))
    n
    (match [k n]
           [1 _] (recur r (*' 2 n))
           [_ 1] (recur (cons (dec k) r) 1)