110 people attended OEIS-50 (videos, suggestions); annual fundraising drive to start soon (donate); editors, please edit! (stack is over 300), your editing is more valuable than any donation.
For n = 6 there are 2 possibilities: A048200(6) = 15. -> Two minimal XR-sequences with length 15 exist. -> "xrxrrxrxrrxrrrx" "rxrrxrxrrxrxrrx"; so a(6) = 2.