something like:
Function Number2Row(Number As Long) As String
' 1 bis 256
Dim OrgValue As Long
Dim newValue As Long
Dim Rest As Long

OrgValue = Number

If Number <= 0 Then
   result = ""
   GoTo finish
End If

'Rest = Number Mod 26

counter = 0
Do While Number > 26
Number = Number - 26
counter = counter + 1
Loop

'If counter = 0 Then counter = 1

newValue = (OrgValue - (counter * 26))

If counter = 0 Then 'einer
   result = Chr$(Number + 64) & Number2Row(OrgValue - 26)
Else ' ab zweiter Stelle
   result = Chr$(counter + 64) & Number2Row(OrgValue - (counter * 26))
End If

finish:
Number2Row = result
End Function