function sierpinski(n : Integer) {
  var down = ["*"];
  var space = " ";
  for (i in [1..n]) {
    down = [for (x in down) "{space}{x}{space}", for (x in down) "{x} {x}"];
    space = "{space}{space}";
  }

  for (x in down) {
    println("{x}")
  }
}

sierpinski(4);