math/perfect_numbers: update deprecated approaches

Author: mertcandav

Algorithms/Math/Perfect_Numbers.fs

@@ -6,7 +6,7 @@ module PerfectNumbers =
         match n with
         | n when n <= 0 -> false
         | n ->
-            { 1 .. n - 1 }
+            seq { 1 .. n - 1 }
             |> Seq.takeWhile (fun i -> i * i <= n)
             |> Seq.filter ((%) n >> (=) 0)
             |> Seq.fold (fun acc i -> acc + i + n / i) 0