Triangle read by rows: T(n,k) is the number of ordered trees with n edges and 2k nodes of odd degree (not outdegree; 1 <= k <= ceiling(n/2)).
A127157
Triangle read by rows: T(n,k) is the number of ordered trees with n edges and 2k nodes of odd degree (not outdegree; 1 <= k <= ceiling(n/2)).
Terms
- a(0) =1a(1) =2a(2) =3a(3) =2a(4) =4a(5) =10a(6) =5a(7) =30a(8) =7a(9) =6a(10) =70a(11) =56a(12) =7a(13) =140a(14) =252a(15) =30a(16) =8a(17) =252a(18) =840a(19) =330a(20) =9a(21) =420a(22) =2310a(23) =1980a(24) =143a(25) =10a(26) =660a(27) =5544a(28) =8580a(29) =2002
External references
- oeis: A127157