Code Wars Ocaml Powers of Two kata

main.ml

let rec power x n =
  match n with
  | 0 -> 1
  | _ -> x * (power x (n - 1))
  
let powersOfTwo n =
  let rec loop acc d =
    match d with
    | 0 -> acc
    | x -> loop (acc @ [power 2 x]) (x - 1)
  in
  List.sort compare (loop [1] n)