#load "nums.cma";;
open Num;;

for candidate = 2 to 1 lsl 19 do
  let sum = ref (num_of_int 1 // num_of_int candidate) in
  for factor = 2 to truncate (sqrt (float candidate)) do
    if candidate mod factor = 0 then
      sum := !sum +/ num_of_int 1 // num_of_int factor
                  +/ num_of_int 1 // num_of_int (candidate / factor)
  done;
  if is_integer_num !sum then
    Printf.printf "Sum of recipr. factors of %d = %d exactly %s\n%!"
        candidate (int_of_num !sum) (if int_of_num !sum = 1 then "perfect!" else "")
done;;