First of two complementary trees generated by the triangular numbers. The second tree is A183232.

Terms

a(0) =1a(1) =4a(2) =3a(3) =19a(4) =7a(5) =13a(6) =6a(7) =229a(8) =25a(9) =43a(10) =11a(11) =118a(12) =18a(13) =34a(14) =10a(15) =26794a(16) =250a(17) =376a(18) =32a(19) =1033a(20) =52a(21) =89a(22) =16a(23) =7258a(24) =133a(25) =208a(26) =24a(27) =664a(28) =42a(29) =76