a(n) = 34*n^2 - 1.

Terms

a(0) =33a(1) =135a(2) =305a(3) =543a(4) =849a(5) =1223a(6) =1665a(7) =2175a(8) =2753a(9) =3399a(10) =4113a(11) =4895a(12) =5745a(13) =6663a(14) =7649a(15) =8703a(16) =9825a(17) =11015a(18) =12273a(19) =13599a(20) =14993a(21) =16455a(22) =17985a(23) =19583a(24) =21249a(25) =22983a(26) =24785a(27) =26655a(28) =28593a(29) =30599