function promo_semana(inicia){
http = createRequestObject(); 
    http.open('get', 'phpajax/busca_promosig.php?inicia='+inicia);
    http.onreadystatechange = function () {
		if(http.readyState == 4){
        var response = http.responseText;
        document.getElementById("propuesta_semana").innerHTML = response;	
        }
     }
    http.send(null);

}