Circular matrix in vb.net

Dim c As Integer = 1
        Dim i, j, k, n, x As Integer
        Dim m As Integer = 0

        n = 5
        x = n

        Dim a(n, n) As Integer

        While n >= 1
            For k = 0 To n - 1
                a(m, k + m) = c
                c = c + 1
            Next

            For k = 1 To n - 1
                a(k + m, n - 1 + m) = c
                c = c + 1
            Next

            For k = n - 2 To 0 Step -1
                a(n - 1 + m, k + m) = c
                c = c + 1
            Next


            For k = n - 2 To 1 Step -1
                a(k + m, m) = c
                c = c + 1
            Next

            n = n - 2
            m = m + 1

        End While

        Dim strB As New StringBuilder

        strB.Append("<table border='1'>")
        For i = 0 To x - 1
            strB.Append("<tr>")
            For j = 0 To x - 1
                strB.Append("<td>")
                strB.Append(a(i, j))
                strB.Append("</td>")
            Next
            strB.Append("</tr>")
        Next
        strB.Append("</table>")

        Response.Write(strB)