a(n) = 2*n*(n+1)*(n+2)/3.

Terms

a(0) =0a(1) =4a(2) =16a(3) =40a(4) =80a(5) =140a(6) =224a(7) =336a(8) =480a(9) =660a(10) =880a(11) =1144a(12) =1456a(13) =1820a(14) =2240a(15) =2720a(16) =3264a(17) =3876a(18) =4560a(19) =5320a(20) =6160a(21) =7084a(22) =8096a(23) =9200a(24) =10400a(25) =11700a(26) =13104a(27) =14616a(28) =16240a(29) =17980