F# getting a list of random numbers

Your code is simply getting one random number and using it ten times.

This extension method might be useful:

type System.Random with
    /// Generates an infinite sequence of random numbers within the given range.
    member this.GetValues(minValue, maxValue) =
        Seq.initInfinite (fun _ -> this.Next(minValue, maxValue))

Then you can use it like this:

let r = System.Random()
let nums = r.GetValues(1, 1000) |> Seq.take 10

let genRandomNumbers count =
    let rnd = System.Random()
    List.init count (fun _ -> rnd.Next ())

let l = genRandomNumbers 10
printfn "%A" l