a(n) = 26*n^2 - 1.

Terms

a(0) =25a(1) =103a(2) =233a(3) =415a(4) =649a(5) =935a(6) =1273a(7) =1663a(8) =2105a(9) =2599a(10) =3145a(11) =3743a(12) =4393a(13) =5095a(14) =5849a(15) =6655a(16) =7513a(17) =8423a(18) =9385a(19) =10399a(20) =11465a(21) =12583a(22) =13753a(23) =14975a(24) =16249a(25) =17575a(26) =18953a(27) =20383a(28) =21865a(29) =23399