Sub Main()
  t = Date
  p = 0
  Do
    If DateValue("2013/12/31") = t Then
      Exit Do
    End If
    If Day(t) = 13 And Weekday(t) = 6 Then
      Range("A1").Offset(p) = t
      p = p + 1
    End If
    t = t + 1
  Loop
End Sub