Total number of edges in all rooted trees on n nodes.

Terms

a(0) =0a(1) =1a(2) =4a(3) =12a(4) =36a(5) =100a(6) =288a(7) =805a(8) =2288a(9) =6471a(10) =18420a(11) =52426a(12) =149832a(13) =428649a(14) =1229354a(15) =3530715a(16) =10157552a(17) =29259703a(18) =84396168a(19) =243698332a(20) =704436640a(21) =2038158801a(22) =5902222810a(23) =17105674632a(24) =49612191480a(25) =143990912750a(26) =418177092554