var randnum = Math.random();
var inum = 13;
var rand1 = Math.round(randnum * (inum-1)) + 1;

images = new Array
images[1] = "http://se-blog.com/wp-content/themes/seblog/images/phones/1.png"
images[2] = "http://se-blog.com/wp-content/themes/seblog/images/phones/2.png"
images[3] = "http://se-blog.com/wp-content/themes/seblog/images/phones/3.png"
images[4] = "http://se-blog.com/wp-content/themes/seblog/images/phones/4.png"
images[5] = "http://se-blog.com/wp-content/themes/seblog/images/phones/5.png"
images[6] = "http://se-blog.com/wp-content/themes/seblog/images/phones/6.png"
images[7] = "http://se-blog.com/wp-content/themes/seblog/images/phones/7.png"
images[8] = "http://se-blog.com/wp-content/themes/seblog/images/phones/8.png"
images[9] = "http://se-blog.com/wp-content/themes/seblog/images/phones/9.png"
images[10] = "http://se-blog.com/wp-content/themes/seblog/images/phones/10.png"
images[11] = "http://se-blog.com/wp-content/themes/seblog/images/phones/11.png"
images[12] = "http://se-blog.com/wp-content/themes/seblog/images/phones/12.png"
images[13] = "http://se-blog.com/wp-content/themes/seblog/images/phones/13.png"

var image = images[rand1]

document.write('<style type="text/css">#sidebar {background: url(' + image + ');background-repeat: no-repeat;}</style>')