for(var i = 0; i < 100; i++){
    var row1 = range('A' + (i + 3));
    var row1Dest = range('A' + (i + 4));
    var row2 = range('B' + (i + 2));
    var row2Dest = range('B' + (i + 3));
    var row3 = range('C' + (i + 1));
    var row3Dest = range('C' + (i + 2));
    var c = 40;

    row1.setValue('');
    row1.setBackground('white');
    row2.setValue('');
    row2.setBackground('white');
    row3.setValue('');
    row3.setBackground('white');
    sleep(100);

    row1Dest.setValue(1);
    row2Dest.setValue(2);
    row3Dest.setValue(3);

    if (i - 3 < 40) {
      row1Dest.setBackground(row1Colours[i]);
      row2Dest.setBackground(row2Colours[i]);
      row3Dest.setBackground(row3Colours[i]);
    } else if (i - 3 >= 40) {
      row1Dest.setBackground(row1Colours[c]);
      row2Dest.setBackground(row2Colours[c]);
      row3Dest.setBackground(row3Colours[c]);
      c--;
    }

    SpreadsheetApp.flush();
    sleep(100);
  }
}