function VecImagenes()
{
  n=0;
  this[n++]="/images/banner.jpg";
  this[n++]="/images/banner2.jpg";
  this[n++]="/images/banner3.jpg";
  this[n++]="/images/banner4.jpg";
  this[n++]="/images/banner5.jpg";
  this[n++]="/images/banner6.jpg";
  this.N=n;
}
var Imagenes=new VecImagenes();
src= Imagenes[ Math.floor(Math.random() * Imagenes.N) ] ;
document.write("<img src="+src+">");