a(0) = 1; thereafter a(n) = 2*(6*n^2 - 3*n + 1).

Terms

a(0) =1a(1) =8a(2) =38a(3) =92a(4) =170a(5) =272a(6) =398a(7) =548a(8) =722a(9) =920a(10) =1142a(11) =1388a(12) =1658a(13) =1952a(14) =2270a(15) =2612a(16) =2978a(17) =3368a(18) =3782a(19) =4220a(20) =4682a(21) =5168a(22) =5678a(23) =6212a(24) =6770a(25) =7352a(26) =7958a(27) =8588a(28) =9242a(29) =9920