Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
If Target.Address <> "$C$1" Then Exit Sub
Dim R As Range, n As Long
'nettoyage colonne C
Columns(3).ClearContents
Cells(1, 3) = "Numéros manquants"
'plage de recherche
Set R = Range("B2:B" & Cells(Rows.Count, 2).End(xlUp).Row)
'pour tester chaque nombre jusqu"au plus grand avec l'équivalent de NB.SI...
For n = 0 To Application.Max(R)
If Application.CountIf(R, n) = 0 Then Range("C" & Cells(Rows.Count, 3).End(xlUp).Row + 1) = n
Next
Cancel = True
End Sub