' version 28-10-2016
' compile with: fbc -s console
' to do A(4, 2) the stack size needs to be increased
' compile with: fbc -s console -t 2000

Function ackerman (m As Long, n As Long) As Long

    If m = 0 Then ackerman = n +1

    If m > 0 Then
        If n = 0 Then
            ackerman = ackerman(m -1, 1)
        Else
            If n > 0 Then
                ackerman = ackerman(m -1, ackerman(m, n -1))
            End If
        End If
    End If
End Function

' ------=< MAIN >=------

Dim As Long m, n
Print

For m = 0 To 4
    Print Using "###"; m;
    For n = 0 To 10
        ' A(4, 1) or higher will run out of stack memory (default 1M)
        ' change n = 1 to n = 2 to calculate A(4, 2), increase stack!
        If m = 4 And n = 1 Then Exit For
        Print Using "######"; ackerman(m, n);
    Next
    Print
Next

' empty keyboard buffer
While InKey <> "" : Wend
Print : Print "hit any key to end program"
Sleep
End