a(n) = (8*n + 1)^2.

Terms

a(0) =1a(1) =81a(2) =289a(3) =625a(4) =1089a(5) =1681a(6) =2401a(7) =3249a(8) =4225a(9) =5329a(10) =6561a(11) =7921a(12) =9409a(13) =11025a(14) =12769a(15) =14641a(16) =16641a(17) =18769a(18) =21025a(19) =23409a(20) =25921a(21) =28561a(22) =31329a(23) =34225a(24) =37249a(25) =40401a(26) =43681a(27) =47089a(28) =50625a(29) =54289