a(n) = 1600*n^2 - 40.

Terms

a(0) =1560a(1) =6360a(2) =14360a(3) =25560a(4) =39960a(5) =57560a(6) =78360a(7) =102360a(8) =129560a(9) =159960a(10) =193560a(11) =230360a(12) =270360a(13) =313560a(14) =359960a(15) =409560a(16) =462360a(17) =518360a(18) =577560a(19) =639960a(20) =705560a(21) =774360a(22) =846360a(23) =921560a(24) =999960a(25) =1081560a(26) =1166360a(27) =1254360a(28) =1345560a(29) =1439960