Sub b()
Application.ScreenUpdating = False
With Range("A1:L1")
.FormulaR1C1 = "=(""1/""&COLUMN())*1"
.Value = .Value
End With
Range("A1:L31").DataSeries Rowcol:=xlColumns, Type:=xlChronological, Date:= _
xlDay, Step:=1, Trend:=False
With Range("A1").CurrentRegion
.NumberFormatLocal = "jjj j/m/aaaa"
.FormatConditions.Delete
.FormatConditions.Add Type:=xlExpression, Formula1:="=JOURSEM(A1;2)>5"
.FormatConditions(1).Interior.ColorIndex = 27
End With
End Sub