The number of trees with 4 nodes labeled by positive integers, where each tree's label sum is n.

Terms

a(0) =2a(1) =4a(2) =10a(3) =17a(4) =30a(5) =44a(6) =67a(7) =91a(8) =126a(9) =163a(10) =213a(11) =265a(12) =333a(13) =403a(14) =491a(15) =582a(16) =693a(17) =807a(18) =944a(19) =1084a(20) =1249a(21) =1418a(22) =1614a(23) =1814a(24) =2044a(25) =2278a(26) =2544a(27) =2815a(28) =3120a(29) =3430