Puzzler of 01/21/2012: What is X in the series 4, 6, 12, 18, 30, 42, 60, X, 102, ...?

I didn’t realize that there were clues in the brackets that would show up if you highlighted them with the cursor (I have no idea how to do that, or any other formatting for that matter since the instructions on how to format these things got discarded with the old system). It appears that I did figure it out, and there does seem to be a pattern that makes some sense, mathematically. However, I don’t understand the “immediate company they keep” hint. I never was too great at math. Perhaps I will ask my pastor about this in the morning since he’s also the professor of mathematics at the local community college.