a(n) = n^4 - n^3.

Terms

a(0) =0a(1) =0a(2) =8a(3) =54a(4) =192a(5) =500a(6) =1080a(7) =2058a(8) =3584a(9) =5832a(10) =9000a(11) =13310a(12) =19008a(13) =26364a(14) =35672a(15) =47250a(16) =61440a(17) =78608a(18) =99144a(19) =123462a(20) =152000a(21) =185220a(22) =223608a(23) =267674a(24) =317952a(25) =375000a(26) =439400a(27) =511758a(28) =592704a(29) =682892