Dim Feuille As Worksheet, Nom As String
For Each Feuille In ThisWorkbook.Worksheets
If Feuille.Index = 1 Then
Feuille.Range("AA40").FormulaR1C1 = "=RC[-7]"
Else
Feuille.Range("AA40").FormulaR1C1 = "='" & Nom & "'!RC[-7]+RC[-7]"
End If
Nom = Feuille.Name
Next Feuille