Fibonacci Series c#

  protected void Page_Load(object sender, EventArgs e)
  {
    int newNum = 0;
    int nextNum = 1;
    int prevNum = -1;

    for (int j = 0; j <= 20; j++)
    {
      newNum = nextNum + prevNum;
      prevNum = nextNum;
      nextNum = newNum;
      Response.Write(newNum + ", ");
    }
  }