Private Sub Worksheet_Change(ByVal Target As Range)
With [B3:B200]
If Not Intersect(Target, .Resize(, 3)) Is Nothing Then 'colonnes B:D
Application.EnableEvents = False
.FormulaR1C1 = "=IF(RC4="""","""",MAX(R2C:R[-1]C)+1)"
.Value = .Value
Application.EnableEvents = True
End If
End With
End Sub