Triangle giving number of labeled trees with n >= 3 nodes and diameter d >= 2.

Terms

a(0) =3a(1) =4a(2) =12a(3) =5a(4) =60a(5) =60a(6) =6a(7) =210a(8) =720a(9) =360a(10) =7a(11) =630a(12) =6090a(13) =7560a(14) =2520a(15) =8a(16) =1736a(17) =47040a(18) =112560a(19) =80640a(20) =20160a(21) =9a(22) =4536a(23) =363384a(24) =1496880a(25) =1829520a(26) =907200a(27) =181440a(28) =10a(29) =11430