a(0) = 1; thereafter a(n) = 4*n^2 - 3*n + 2.

Terms

a(0) =1a(1) =3a(2) =12a(3) =29a(4) =54a(5) =87a(6) =128a(7) =177a(8) =234a(9) =299a(10) =372a(11) =453a(12) =542a(13) =639a(14) =744a(15) =857a(16) =978a(17) =1107a(18) =1244a(19) =1389a(20) =1542a(21) =1703a(22) =1872a(23) =2049a(24) =2234a(25) =2427a(26) =2628a(27) =2837a(28) =3054a(29) =3279