Number of ordered trees with n edges and with no vertex of outdegree 2 that have two leaves as their two children.
A178520
Number of ordered trees with n edges and with no vertex of outdegree 2 that have two leaves as their two children.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =4a(4) =11a(5) =32a(6) =98a(7) =309a(8) =998a(9) =3285a(10) =10981a(11) =37178a(12) =127227a(13) =439369a(14) =1529280a(15) =5359314a(16) =18894435a(17) =66967086a(18) =238473876a(19) =852825314a(20) =3061529014a(21) =11028596473a(22) =39853923390a(23) =144435373636a(24) =524837483375
External references
- oeis: A178520