@Html.TextBoxFor for repeated properties in the model
Public Class SampleData
    Public Property PTY_1 as String
    Public Property PTY_2 as String
    Public Property PTY_3 as String
    '...snipped
    Public Property PTY_19 as String
    Public Property PTY_20 as String
End Class

<tr><td>@Html.TextBoxFor(Function(model) model.PTY_1)</td></tr>
<tr><td>@Html.TextBoxFor(Function(model) model.PTY_2)</td></tr>
<tr><td>@Html.TextBoxFor(Function(model) model.PTY_3)</td></tr>
'...snipped
<tr><td>@Html.TextBoxFor(Function(model) model.PTY_19)</td></tr>
<tr><td>@Html.TextBoxFor(Function(model) model.PTY_20)</td></tr>

Public Class SampleData
    Public Property PTY(index as Integer) as String
        Get
            Select Case index
                Case 1 : Return PTY_1
                Case 2 : Return PTY_2
                Case 3 : Return PTY_3
                '...snipped
                Case 19 : Return PTY_19
                Case 20 : Return PTY_20
                Case Else : Return ""
            End Select
        End Get
        Set (value as String)
            Select case index
                Case 1 : PTY_1 = value
                Case 2 : PTY_2 = value
                Case 3 : PTY_3 = value
                '...snipped
                Case 19 : PTY_19 = value
                Case 20 : PTY_20 = value
            End Select
        End Set
    End Property
End Class

@For index as Integer = 1 to 20
    <tr><td>@Html.TextBoxFor(Function(model) model.PTY(index))</td></tr>
End For

@Html.EditorForModel()

<DataType(DataType.MultilineText)> _
<UIHint("CustomTextArea")> _
Public Property PTY_1 as String

...

<tr><td>@Html.TextArea("")</td></tr>

@for (int i = 1; i <= 20; i++)
{
    string name = "PTY_" + i;
    <tr><td><input type="text" name="@name" /></td></tr>
}