What would be an elegant way to implement the functionality of this nested class in F#?

  private class Aliaser {
     private int _count;
     internal Aliaser() { }
     internal string GetNextAlias() {
        return "t" + (_count++).ToString();
     }
  }

This was my first attempt, but it feels like there should be a sexy one-liner for this:

let aliases = (Seq.initInfinite (sprintf "t%d")).GetEnumerator()

let getNextAlias() = 
    aliases.MoveNext() |> ignore
    aliases.Current