Sub test()
Dim d As Object
Dim i As Long
Dim ar
On Error Resume Next
Set d = CreateObject("scripting.dictionary")
ar = Range("a1:a" & Range("a65536").End(xlUp).Row)
For i = 1 To UBound(ar)
d(ar(i, 1)) = ""
Next i
Sheet2.Range("b:b").Clear
Sheet2.Range("b1").Resize(d.Count, 1) = Application.Transpose(d.keys)
End Sub