This is a strategy for the rings in loops in general. It should be for loops other than 1-1 and 2-2 loops. Like 1-3, 2-4 and so on (bigger).
Give +1 if loop ring on both sides is all A’s.
Give -1 if there on both sides of the ring is bases that attract each other and want to pair up like AU’s, GU’s and GC’s. Often the two last ends up pairing up elsewhere outside of the loop ring. Give -1 pr each extra possible basepair.
Give -1 if there is basepairs on each side of the loop ring, that rejects each other. -1 pr. each rejects. Penalize if two blue, two green or two red is opposite each other in loop ring.