Public Class Form1
    Dim n, a, b As Integer
    Dim dx, dy, x, y As Single
    Dim gr As Graphics
    Dim penr As New Pen(Brushes.Black, 2)

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        gr = PictureBox1.CreateGraphics
        gr.Clear(Color.White)
        n = TextBox1.Text
        a = 400
        x = 10
        y = 10
        Timer1.Start()
        'Цикл рисования
        For i = 1 To n
            gr.DrawRectangle(penr, x, y, a, a)
            gr.DrawEllipse(penr, x, y, a, a)
            b = Math.Sqrt((a / 2 * a / 2) + (a / 2 * a / 2))
            dx = (a - b) / 2
            dy = (a - b) / 2
            x = x + dx
            y = y + dy
            a = b
        Next


    End Sub