a(n) = -2*n^2 + 12*n - 14.

Terms

a(0) =-4a(1) =2a(2) =4a(3) =2a(4) =-4a(5) =-14a(6) =-28a(7) =-46a(8) =-68a(9) =-94a(10) =-124a(11) =-158a(12) =-196a(13) =-238a(14) =-284a(15) =-334a(16) =-388a(17) =-446a(18) =-508a(19) =-574a(20) =-644a(21) =-718a(22) =-796a(23) =-878a(24) =-964a(25) =-1054a(26) =-1148a(27) =-1246a(28) =-1348a(29) =-1454