let [|m; n|] = stdin.ReadLine().Split " " |> Array.map int

let rec e = function
    | 0 -> float m
    | n ->
        let prev = e (n-1)
        1./3. * prev * 2. + 1./3. * (prev + 1.) + 1./3. * 0.
        
e n |> printfn "%f"