(*
By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6^(th) prime is 13.

What is the 10001^(st) prime number?
*)

let pn =
  let rec searchpn x ps =
    if( List.length ps = 10001) then (List.hd ps) else
    if( List.exists (fun y->(x mod y=0)) ps)
    then searchpn (x+1) ps
    else searchpn (x+1) (x::ps)
  in
    searchpn 2 []
;;

Printf.printf "%d\n" pn;;