' limit: k * n +1 must be smaller then 2^32-1

Function pow_mod(b As ULongInt, power As ULongInt, modulus As ULongInt) As ULongInt
    ' returns b ^ power mod modulus
    Dim As ULongInt x = 1

    While power > 0
        If (power And 1) = 1 Then
            x = (x * b) Mod modulus
        End If
        b = (b * b) Mod modulus
        power = power Shr 1
    Wend

    Return x

End Function


For k As ULongInt= 2 To 10 Step 2
    Print "The first 50 Curzon numbers using a base of "; k; ":"
    Dim As ULongInt count, n = 1, p, m

    Do
        m = k * n +1
        p = pow_mod(k, n ,m) +1
        If p = m Then
            count += 1
            If count <= 50 Then
                Print Using "#####"; n;
                If (count Mod 10) = 0 Then Print
            ElseIf count = 1000 Then
                Print : Print "One thousandth: "; n
                Print : Print
                Exit Do
            End If
        End If
        n += 1
    Loop

Next
Sleep