conway-PM.clj

(import [java.math BigInteger])

(defn conway-PM []
  (let [factors [17/91 78/85 19/51 23/38 29/33 77/29 95/23 
		 77/19 1/17 11/13 13/11 15/14 15/2 55/1]
	big-int (fn [n];"makes a bigint from int, if needed"
		  (if (instance? BigInteger n)
		    n (BigInteger/valueOf n)))
	special-log (fn [n]; base 2 log of n iff n = 2^m, else nil
		      (let [bn (big-int n)]
			(if (= (.bitCount #^BigInteger bn) 1)
			  (- (.bitLength #^BigInteger bn) 1))))
	step ;"Multiplies with the first factor to give an integer."
	     (fn [n, unused-factors] 
	       (let [factor (first unused-factors)
		     rest-factors (rest unused-factors)
		     dummy (* n factor)]
		 (if (integer? dummy) 
		   dummy
		   (recur n rest-factors))))]
    (iterate #(step % factors) 2)))