a(n) = (n/2)*(n^4 + 1).

Terms

a(0) =0a(1) =1a(2) =17a(3) =123a(4) =514a(5) =1565a(6) =3891a(7) =8407a(8) =16388a(9) =29529a(10) =50005a(11) =80531a(12) =124422a(13) =185653a(14) =268919a(15) =379695a(16) =524296a(17) =709937a(18) =944793a(19) =1238059a(20) =1600010a(21) =2042061a(22) =2576827a(23) =3218183a(24) =3981324a(25) =4882825a(26) =5940701a(27) =7174467a(28) =8605198a(29) =10255589