Dim Shared As Long lastsquare, nextsquare, lastcube, midcube, nextcube

Function squares() As Long
    lastsquare += nextsquare
    nextsquare += 2
    squares = lastsquare
End Function

Function cubes() As Long
    lastcube += nextcube
    nextcube += midcube
    midcube += 6
    cubes = lastcube
End Function

lastsquare = 1 : nextsquare = -1 : lastcube = -1 : midcube = 0 : nextcube = 1
Dim As Long cube, square
cube = cubes

For i As Byte = 1 To 30
    Do
        square = squares
        Do While cube < square
            cube = cubes
        Loop
        If square <> cube Then Exit Do
    Loop
    If i > 20 Then Print square;
Next i
Sleep