Triangle read by rows: T(n,k) is the number of 0-1-2 trees (i.e., ordered trees with all vertices of outdegree at most two) with n edges and k pairs of adjacent vertices of outdegree 2.
A126218
Triangle read by rows: T(n,k) is the number of 0-1-2 trees (i.e., ordered trees with all vertices of outdegree at most two) with n edges and k pairs of adjacent vertices of outdegree 2.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =4a(4) =7a(5) =2a(6) =13a(7) =8a(8) =26a(9) =20a(10) =5a(11) =52a(12) =50a(13) =25a(14) =104a(15) =130a(16) =75a(17) =14a(18) =212a(19) =322a(20) =217a(21) =84a(22) =438a(23) =770a(24) =644a(25) =294a(26) =42a(27) =910a(28) =1836a(29) =1806
External references
- oeis: A126218