a(n) = n^2*(2*n - 3 - (-1)^n)/4.

Terms

a(0) =0a(1) =0a(2) =9a(3) =16a(4) =50a(5) =72a(6) =147a(7) =192a(8) =324a(9) =400a(10) =605a(11) =720a(12) =1014a(13) =1176a(14) =1575a(15) =1792a(16) =2312a(17) =2592a(18) =3249a(19) =3600a(20) =4410a(21) =4840a(22) =5819a(23) =6336a(24) =7500a(25) =8112a(26) =9477a(27) =10192a(28) =11774a(29) =12600