Calculate prime numbers using erathosphen method

ErathosphensSieve.fs

// Calculate prime numbers using erathosphen method
open System.Collections.Generic

let erathosphensSieve  n = 
    let numbers = ResizeArray [|2..n|]    
    let mutable p = 2
    let mutable ready = false
    while not ready do 
        match Seq.tryFindIndex (fun x -> x >= p * p) numbers with
        | None -> 
            ready <- true
        | Some n -> 
            let mutable n = n
            let mutable len = numbers.Count
            while len > 0 && n < len do
                if numbers.[n] % p = 0 then
                    numbers.RemoveAt n
                    len <- len - 1
                else
                    n <- n + 1  
            //printfn "p = %d" p
            //Seq.iteri (printfn "[%d] : %d") numbers                 
            match Seq.tryFind( fun x -> x > p) numbers with
            | None -> 
                ready <- true
            | Some x -> 
                p <- x
    numbers
      
erathosphensSieve 31 |> Seq.toList = [2; 3; 5; 7; 11; 13; 17; 19; 23; 29; 31]
erathosphensSieve 41 |> Seq.toList = [2; 3; 5; 7; 11; 13; 17; 19; 23; 29; 31; 37; 41]