a(n) = 21*n^2 - 33*n + 13.

Terms

a(0) =1a(1) =31a(2) =103a(3) =217a(4) =373a(5) =571a(6) =811a(7) =1093a(8) =1417a(9) =1783a(10) =2191a(11) =2641a(12) =3133a(13) =3667a(14) =4243a(15) =4861a(16) =5521a(17) =6223a(18) =6967a(19) =7753a(20) =8581a(21) =9451a(22) =10363a(23) =11317a(24) =12313a(25) =13351a(26) =14431a(27) =15553a(28) =16717a(29) =17923