a(n) = 400*n^2 - 20.

Terms

a(0) =380a(1) =1580a(2) =3580a(3) =6380a(4) =9980a(5) =14380a(6) =19580a(7) =25580a(8) =32380a(9) =39980a(10) =48380a(11) =57580a(12) =67580a(13) =78380a(14) =89980a(15) =102380a(16) =115580a(17) =129580a(18) =144380a(19) =159980a(20) =176380a(21) =193580a(22) =211580a(23) =230380a(24) =249980a(25) =270380a(26) =291580a(27) =313580a(28) =336380a(29) =359980