void setup() {
  size(640, 640);
  background(255);
  smooth();
  noFill();

  translate(width/2, height/2);
  drawCircle(0, 0, 300);
}

void drawCircle(int x, int y, int s) {
  if (s>2) {
    ellipse(x, y, s, s);
    drawCircle(x-s/2, y, s/2);
    drawCircle(x+s/2,y,s/2);
    drawCircle(x,y+s/2,s/2);
    drawCircle(x,y-s/2,s/2);
  }
}