a(n) = (7*n + 4)^2.

Terms

a(0) =16a(1) =121a(2) =324a(3) =625a(4) =1024a(5) =1521a(6) =2116a(7) =2809a(8) =3600a(9) =4489a(10) =5476a(11) =6561a(12) =7744a(13) =9025a(14) =10404a(15) =11881a(16) =13456a(17) =15129a(18) =16900a(19) =18769a(20) =20736a(21) =22801a(22) =24964a(23) =27225a(24) =29584a(25) =32041a(26) =34596a(27) =37249a(28) =40000a(29) =42849