Triangle read by rows: counts ordered trees by number of edges and position of first edge that terminates at a vertex of outdegree 1.

A098977

Triangle read by rows: counts ordered trees by number of edges and position of first edge that terminates at a vertex of outdegree 1.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =2a(4) =2a(5) =1a(6) =4a(7) =5a(8) =3a(9) =2a(10) =9a(11) =14a(12) =9a(13) =6a(14) =4a(15) =21a(16) =42a(17) =28a(18) =19a(19) =13a(20) =9a(21) =51a(22) =132a(23) =90a(24) =62a(25) =43a(26) =30a(27) =21a(28) =127a(29) =429

External references