Triangle read by rows: T(n,k) is the number of peakless Motzkin paths of length n containing k subwords of the type U H^j U or D H^j D for some j>0, where U=(1,1), H=(1,0) and D=(1,-1) (can be easily expressed using RNA secondary structure terminology).

A097100

Triangle read by rows: T(n,k) is the number of peakless Motzkin paths of length n containing k subwords of the type U H^j U or D H^j D for some j>0, where U=(1,1), H=(1,0) and D=(1,-1) (can be easily expressed using RNA secondary structure terminology).