a(n) = (3n+2)^2.

Terms

a(0) =1a(1) =4a(2) =25a(3) =64a(4) =121a(5) =196a(6) =289a(7) =400a(8) =529a(9) =676a(10) =841a(11) =1024a(12) =1225a(13) =1444a(14) =1681a(15) =1936a(16) =2209a(17) =2500a(18) =2809a(19) =3136a(20) =3481a(21) =3844a(22) =4225a(23) =4624a(24) =5041a(25) =5476a(26) =5929a(27) =6400a(28) =6889a(29) =7396