Find all possible combinations of letters

Where do you want the output? I now used range A1:A

Sub AllOptions()
Dim character As Integer 'Asc("a")=97, Asc("h")=104
Dim i, j, k As Long
Dim RowCounter
  RowCounter = 1
  For i = Asc("a") To Asc("h")
    For j = Asc("a") To Asc("h")
      For k = Asc("a") To Asc("h")
        If Abs(i - j) > 1 Or Abs(j - k) > 1 Then
          If i <> j And j <> k And i <> k Then
            Cells(RowCounter, 1) = Chr(i) & Chr(j) & Chr(k)
            RowCounter = RowCounter + 1
          End If
        End If
      Next k
    Next j
Next i
End Sub

here some code that will make you patient

Sub TakesTooLong()
Dim a As Long
Dim LeftVal As Long, Rightval As Long, val As Long
Dim PreviousPos As Long
Dim NotOk As Boolean
Dim RowCounter As Long
Dim ValStr As String
Application.ScreenUpdating = False
RowCounter = 1 'used for printing
For val = 11111111 To 88888888 'Asc("a")=97 (now=1), Asc("h")=104 (now=8)
  ValStr = ""
  NotOk = False
  PreviousPos = -1
  For a = 1 To 7
    LeftVal = CLng(Mid(CStr(val), a, 1))
    Rightval = CLng(Mid(CStr(val), a + 1, 1))
    If LeftVal = 9 Or LeftVal = 0 Or Rightval = 9 Or Rightval = 0 Then
      NotOk = True
      Exit For  'only a-h equals 1-8 allowed
    ElseIf LeftVal - Rightval = 0 Then 'The same
      NotOk = True
      Exit For
    ElseIf Abs(LeftVal - Rightval) = 1 Then 'one char different
      If a - PreviousPos = 1 Then 'two in a row
        NotOk = True
        Exit For
      Else
        PreviousPos = a
      End If
    End If
  Next a
  If Not NotOk Then
    For a = 1 To 8
      ValStr = ValStr & Chr(Mid(CStr(val), a, 1) + 96)
    Next a
    'Cells(Int(RowCounter / 100) + 1, RowCounter Mod 100 + 1) = ValStr
    RowCounter = RowCounter + 1
  End If
Next val
Application.ScreenUpdating = True
debug.print RowCounter & " Possibilities"
End Sub

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