var $logoList;
var index;

function fade(){
    $($logoList[index]).fadeIn('slow').delay(6000).fadeOut('slow',function(){
        // Set index next partner logo if last get first index again...
        if(index < ($logoList.length - 1)){
            index++;
        } else {
            index = 0;
        }
        // Fade after callback (recursive loop)
        fade();
    })
}

$(document).ready(function(){
    $('.partner_logo img').css('display', 'none');
    // Get all partner logos
    $logoList = $('.partner_logo img');
    // Set random index between "0" and "total of logos"
    var min = 0;
    var max = $logoList.length - 1;
    index = Math.round(min + ((max - min)*(Math.random())));
    // Begin fade
    fade();
});