Const As Double pp = 1.324717957244746025960908854
Const As Double ss = 1.0453567932525329623

Function padovan1(Byval n As Integer) As Integer
    Dim As Integer a, b, c, d, i
    a = 1: b = 1: c = 1
    d = 1
    For i = 1 To (n - 3)
        d = a + b
        a = b : b = c : c = d
    Next i
    Return d
End Function

Function padovan2(Byval n As Integer) As Integer
    Dim As Double p = 1.0
    For i As Integer = 1 To (n - 1)
        p *= pp
    Next i
    Return Fix(p / ss)
End Function

Function padovan3(Byval n As Integer) As String
    Dim As String sgte, s = "A"
    Dim As Integer i, j, c
    Dim As String rules(1 To 3) = {"B", "C", "AB"}

    For i = 1 To n
        sgte = ""
        For j = 1 To Len(s)
            Select Case Mid(s, j, 1)
            Case "A" : c =  1
            Case "B" : c =  2
            Case "C" : c =  3
            End Select
            sgte &= rules(c)
        Next j
        s = sgte
    Next i
    Return s
End Function

Dim As Integer n
Print "First 20 terms of the Padovan sequence:"
For n = 1 To 20
    Print padovan1(n); '" ";
Next

n = 1
Dim As Boolean areEqual = True
Dim As Integer list1(64), list2(64)

Do While n <= 64 And areEqual = False
    list1(n) = padovan1(n)
    list2(n) = padovan2(n)
    If list1(n) <> list2(n) Then areEqual = False
    n += 1
Loop
Print !"\nThe first 64 iterative and calculated values ";
Print Iif(areEqual, "are the same.", "differ.")

Print !"\nFirst 10 L-system strings:"
For n = 0 To 9
    Print padovan3(n); " ";
Next
Print

areEqual = True
Dim As Integer list3(31)

Print !"\nLengths of the 32 first L-system strings:"
For n = 0 To 31
    list3(n) = Len(padovan3(n))
    Print list3(n); '" ";
    If list3(n) <> list1(n) Then areEqual = False
Next
Print !"\nThese lengths are";
Print Iif(areEqual, " the 32 first terms of the Padovan sequence.", " not the 32 first terms of the Padovan sequence.")

Sleep