repeat.js

(function(rows, cols) {

  function group(rows, cols, i) {

    function xValue(i) {
      if (i % cols == 0) {
        return Math.min(3, cols);
      } else if (i % cols == 1) {
        return 1;
      }
      return 2;
    }

    function yValue(i) {
      if (i <= cols) {
        return 0;
      } else if (i > (rows - 1) * cols) {
        return Math.min(3, cols) * ((rows > 2) ? 2 : 1);
      }
      return Math.min(3, cols);
    }

    return xValue(i) + yValue(i);
  }

  var output = "";
  for (var i = 1; i <= rows * cols; i++) {
    output += "repeat:" + i + " group:" + group(rows, cols, i) + "<br>";
  }
  document.body.innerHTML = output;

})(6, 1);