How to have a list of numbers that skip when it gets to certain values?

Nibmus 

Sub fill()

Dim start_variant As Variant
Dim bereich As Range
Dim result_variant As Variant
Dim i As Long
Dim k As Long
Dim number As Long
Dim rows_result_variant As Long

Range("C:C").Clear

Set bereich = Range("A1:A7500")
start_variant = bereich

rows_result_variant = Application.WorksheetFunction.CountA(bereich)

ReDim Preserve start_variant(1 To 7500, 1 To 1)

ReDim result_variant(1 To rows_result_variant, 1)
k = 1
For i = 1 To 7500
If Cells(i, 1) <> "" Then
result_variant(k, 1) = Cells(i, 1).Value
k = k + 1

Else
End If

Next i

number = 1
For i = 1 To 7500

If Cells(i, 1) = "" Then

For k = 1 To rows_result_variant

If result_variant(k, 1) = number Then
number = number + 1
k = 0

Else
End If

Next k
start_variant(i, 1) = number
number = number + 1

Else
End If

Next i

Range("C1:C7500") = start_variant

End Sub

Maybe with this code. In the attached file you can enter unique numbers in range A1:A7500. Then you can click the button in cell E2 to run the code.