// a function to generate the fibonacci numbers
let rec fib x =
    match x with
    | 1 -> 1
    | 2 -> 1
    | x -> fib (x - 1) + fib (x - 2)

// call the function and print the results
printfn "(fib 2) = %i" (fib 2)
printfn "(fib 6) = %i" (fib 6)
printfn "(fib 11) = %i" (fib 11)