Private Sub Worksheet_Change(ByVal Target As Range)
    Dim r As Long, c As Long, v As Long, i As Long
    
    If Target.CountLarge <> 1 Then Exit Sub
    Application.EnableEvents = False
    Application.ScreenUpdating = False
    Application.Calculation = xlCalculationManual
    On Error GoTo Error_exit

    r = Target.Row
    c = Target.Column
    v = Val(Target.Value)
    For i = v - 1 To 0 Step -1
        Range(Cells(WorksheetFunction.Max(r - i, 1), WorksheetFunction.Max(c - i, 1)), _
            Cells(WorksheetFunction.Min(r + i, Rows.Count), WorksheetFunction.Min(c + i, Columns.Count))).Value = v - i
    Next i

Error_exit:
    Application.Calculation = xlCalculationAutomatic
    Application.ScreenUpdating = True
    Application.EnableEvents = True
End Sub

Private Sub Worksheet_Change(ByVal Target As Range)
    Dim iOffs&, iCol&, x&, i&, r As Range
    If Target.CountLarge <> 1 Then Exit Sub
    If Len(Target) = 0 Then Exit Sub
    If Not IsNumeric(Target) Then Exit Sub
    On Error GoTo End_
    x = Target.Value
    iOffs = 1
    Application.EnableEvents = False
    Do
        Set r = Target.Offset(-iOffs, -iOffs).Resize(iOffs * 2 + 1, iOffs * 2 + 1)
        iCol = r.Columns.Count
        r(1) = x    'Target - 1
        For i = 1 To iCol
            r(1, i) = x
            x = x - 1
            If x < 0 Then GoTo End_
        Next
        For i = 2 To iCol
            r(i, iCol) = x
            x = x - 1
            If x < 0 Then GoTo End_
        Next
        For i = iCol - 1 To 1 Step -1
            r(iCol, i) = x
            x = x - 1
            If x < 0 Then GoTo End_
        Next
        For i = iCol - 1 To 2 Step -1
            r(i, 1) = x
            x = x - 1
            If x < 0 Then GoTo End_
        Next
        iOffs = iOffs + 1
        DoEvents
    Loop
End_:
    Application.EnableEvents = True
End Sub