Sub test()
Dim i As Integer, existe As Boolean, noFeuilleRecherche As Integer, celluleValeur As Range, feuille
With ThisWorkbook.Sheets("Table")
For i = 2 To .Cells(.Rows.Count, 1).End(xlUp).Row
existe = False
For noFeuilleRecherche = 1 To 3
Set celluleValeur = Nothing
Set celluleValeur = ThisWorkbook.Sheets(CStr(noFeuilleRecherche)).Cells.Find(what:=.Cells(i, 1).Value, LookIn:=xlValues, lookat:=xlWhole)
If Not celluleValeur Is Nothing Then existe = True
Next noFeuilleRecherche
If existe Then
.Cells(i, 2).Value = "KO"
For noFeuilleRecherche = 1 To ThisWorkbook.Sheets.Count
If ThisWorkbook.Sheets(noFeuilleRecherche).Name = .Cells(i, 1).Value Then .Cells(i, 2).Value = "OK"
Next noFeuilleRecherche
End If
Next i
End With
End Sub