If you log into AC, Log into the Admin section, then go into the Import/Export section, there is a place to export Patient Demographics. This may be slightly different menu path in 6.3.3. It has been a while.
Another approach is to query the database directly and return a report of the date last seen for each patient, which you can then sort. Because we have access to the database, I typically choose the most direct path to a result.
Let me know if you still need some help getting what you need.
