a(n) = 54*n^2 - 1.

Terms

a(0) =53a(1) =215a(2) =485a(3) =863a(4) =1349a(5) =1943a(6) =2645a(7) =3455a(8) =4373a(9) =5399a(10) =6533a(11) =7775a(12) =9125a(13) =10583a(14) =12149a(15) =13823a(16) =15605a(17) =17495a(18) =19493a(19) =21599a(20) =23813a(21) =26135a(22) =28565a(23) =31103a(24) =33749a(25) =36503a(26) =39365a(27) =42335a(28) =45413a(29) =48599