The best way to track subscriptions is through Google Feedburner, which redirects your RSS feed. The only downside is that if you're transmitting your feed elsewhere, say a tool that posts to your Twitter or Yahoo Pipes, those bots/scripts will show up as subscribers and will skew the results slightly.
Best Answer
Try linking to the current version of MathJax, without any parameters, and see if that works:
<script src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.3/MathJax.js" type="text/javascript"></script>
Some other CDNs that host MathJax include:
(This list is from the MathJax docs.)