Hash-ish

HTML

<input type="number" placeholder="height">
<p></p>

CSS

p {
  text-align: right;
}

JavaScript

$('input').change(function() {
  var height = $(this).val();
  $('p').html('');
  for (var i = 0; i < height; i++) {
    $('p').append(
      `${'#'.repeat(i + 2)} <br />`
    );
  }
});