a(n) = (2*n)^2 - 4.

Terms

a(0) =0a(1) =12a(2) =32a(3) =60a(4) =96a(5) =140a(6) =192a(7) =252a(8) =320a(9) =396a(10) =480a(11) =572a(12) =672a(13) =780a(14) =896a(15) =1020a(16) =1152a(17) =1292a(18) =1440a(19) =1596a(20) =1760a(21) =1932a(22) =2112a(23) =2300a(24) =2496a(25) =2700a(26) =2912a(27) =3132a(28) =3360a(29) =3596