Public Function Contains(col As Collection, vl As Variant) As Boolean
    Contains = False
    Dim index As Integer
    For index = 1 To col.count
       If col(index) = vl Then Contains = True: Exit For
    Next index
End Function

Dim fc%, i1%, i2%, i3%, i4%
 
fc = FreeFile
 
'1. Ermittlung der Werte in Spalte 1 und Spalte 4
Open "C:\daten\demodaten.txt" For Input As #fc
 
Dim i1_col As New Collection, i4_col As New Collection
While Not EOF(fc)
 
  Input #fc, i1, i2, i3, i4
  If Not Contains(i1_col, i1) Then i1_col.Add i1
  If Not Contains(i4_col, i4) Then i4_col.Add i4
 
Wend
 
Close #fc
 
'2. gefilterte Häufigkeit der Zahlenkombinationen in Spalte 2 / 3
Open "C:\daten\demodaten.txt" For Input As #fc
 
Dim i2_col As New Collection, i3_col As New Collection
Dim freq(10000) As Integer
 
Dim index As Integer, count As Integer, vorhanden As Boolean
While Not EOF(fc)
   Input #fc, i1, i2, i3, i4
   vorhanden = False
   If Not (Contains(i1_col, i2) Or Contains(i1_col, i3) _
      Or Contains(i4_col, i2) Or Contains(i4_col, i3)) Then
 
      vorhanden = False
      For index = 1 To i2_col.count
         If i2_col(index) = i2 And i3_col(index) = i3 Then
            freq(index) = freq(index) + 1: vorhanden = True: Exit For
         End If
      Next index
 
      If Not vorhanden Then
         i2_col.Add (i2): i3_col.Add (i3): freq(i2_col.count) = 1
      End If
   Else
      'Bedingung: gefilterter Datensatz
      '.....
   End If
Wend
 
Close #fc
 
'3. Füllen der Ergebnisdatei: gefilterte Zahlenkombis, Häufigkeiten
Open "C:\daten\demoresult.txt" For Output As #fc
 
For index = 1 To i2_col.count
   Print #1, CStr(i2_col(index)) & " - " & CStr(i3_col(index)) & _
   ": " & CStr(freq(index))
Next index
 
Close #fc