Number of Motzkin paths of length n, starting with an up step, ending with a down step and having no peaks (can be easily expressed using RNA secondary structure terminology).

A097779

Number of Motzkin paths of length n, starting with an up step, ending with a down step and having no peaks (can be easily expressed using RNA secondary structure terminology).

Terms

    a(0) =1a(1) =0a(2) =0a(3) =1a(4) =1a(5) =2a(6) =5a(7) =11a(8) =25a(9) =58a(10) =135a(11) =317a(12) =750a(13) =1785a(14) =4272a(15) =10275a(16) =24823a(17) =60210a(18) =146576a(19) =358010a(20) =877087a(21) =2154751a(22) =5307166a(23) =13102511a(24) =32418806a(25) =80375267a(26) =199650310a(27) =496803811a(28) =1238276667a(29) =3091173482

External references