def bresenham_circle_octant(radius):
    """
    Uses Bresenham's algorithm to draw a single octant of a circle with thickness 1,
    centered on the origin and with the given radius.
    :param radius: The radius of the circle to draw
    :return: A list of integer coordinates representing pixels.
    Starts at (radius, 0) and end with a pixel (x, y) where x == y.
    """
    x, y = radius, 0
    r2 = radius * radius
    coords = []
    while x >= y:
        coords.append((x, y))
        y += 1
        if abs((x - 1) * (x - 1) + y * y - r2) < abs(x * x + y * y - r2):
            x -= 1
    # add a point on the line x = y at the end if it's not already there.
    if coords[-1][0] != coords[-1][1]:
        coords.append((coords[-1][0], coords[-1][0]))
    return coords