Triangle read by rows: number of 0-1-2 trees (i.e., ordered trees with vertices of outdegrees 0, 1, or 2) with n edges and exactly k vertices that have 2 children, both being leaves (n >= 0, 0 <= k <= floor((n+2)/4)).
A126191
Triangle read by rows: number of 0-1-2 trees (i.e., ordered trees with vertices of outdegrees 0, 1, or 2) with n edges and exactly k vertices that have 2 children, both being leaves (n >= 0, 0 <= k <= floor((n+2)/4)).
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =3a(5) =1a(6) =6a(7) =3a(8) =14a(9) =7a(10) =33a(11) =17a(12) =1a(13) =79a(14) =45a(15) =3a(16) =194a(17) =117a(18) =12a(19) =482a(20) =313a(21) =40a(22) =1214a(23) =843a(24) =129a(25) =2a(26) =3090a(27) =2287a(28) =411a(29) =10
External references
- oeis: A126191