(define (b x)
  (if (< 1 x)
   (+ 3 (b (/ x 1000)))
   x))

(define (main)
 (let loop [(i 1000)
	    (s 0)]
   (if (> i 0)
       (loop (sub1 i) (+ s (b s) 1))
       (print s))))

(time (main))