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

Terms

a(0) =4a(1) =12a(2) =28a(3) =52a(4) =84a(5) =124a(6) =172a(7) =228a(8) =292a(9) =364a(10) =444a(11) =532a(12) =628a(13) =732a(14) =844a(15) =964a(16) =1092a(17) =1228a(18) =1372a(19) =1524a(20) =1684a(21) =1852a(22) =2028a(23) =2212a(24) =2404a(25) =2604a(26) =2812a(27) =3028a(28) =3252a(29) =3484