a(n) is the Wiener index of a broom on 2n vertices of which n+2 are pendant.

Terms

a(0) =25a(1) =54a(2) =100a(3) =167a(4) =259a(5) =380a(6) =534a(7) =725a(8) =957a(9) =1234a(10) =1560a(11) =1939a(12) =2375a(13) =2872a(14) =3434a(15) =4065a(16) =4769a(17) =5550a(18) =6412a(19) =7359a(20) =8395a(21) =9524a(22) =10750a(23) =12077a(24) =13509a(25) =15050a(26) =16704a(27) =18475a(28) =20367a(29) =22384