function image() {};

image = new image();
number = 0;
image[number++] = "<img src='imagenes/indeximagen1.jpg' border='0'>"
image[number++] = "<img src='imagenes/indeximagen2.jpg' border='0'>"
image[number++] = "<img src='imagenes/indeximagen3.jpg' border='0'>"
image[number++] = "<img src='imagenes/indeximagen4.jpg' border='0'>"
image[number++] = "<img src='imagenes/indeximagen5.jpg' border='0'>"

increment = Math.floor(Math.random() * number);