Sum of all Wiener indices of "chemical" trees described by A000602(n).

Terms

a(0) =0a(1) =1a(2) =4a(3) =19a(4) =54a(5) =155a(6) =432a(7) =1252a(8) =3384a(9) =9714a(10) =26752a(11) =75836a(12) =213058a(13) =603791a(14) =1702868a(15) =4830747a(16) =13666890a(17) =38742120a(18) =109715858a(19) =310884129a(20) =880368618a(21) =2493252951a(22) =7058102770a(23) =19978082407a(24) =56531061316a(25) =159932660960a(26) =452354328946