$portion5 = Url::get_portion(5);
    $array_portions = array(0,20,40,60,80,100,120,160,180,200);

    for ($y = 1; $y <= $array_portions.length; $y++) {
        if($array_portions[0] == $portion5){
            for ($i=$array_portions[0]+1; $i<=$array_portions[0]+20; $i++)
            {
                ?>

                    <a href="<?=CONTEXT_NAME?>images/eventos/<?=$data['evento'][0]['id']?>n<?=$i?>.jpg" rel="sexylightbox"  ><img src="<?=CONTEXT_NAME?>images/eventos/varias_fotos/<?=$data['evento'][0]['id']?>n<?=$i?>.jpg" alt=""/></a>

                <?php
            }
        }
    }