Perfect squares in A005728.

Terms

a(0) =1a(1) =81a(2) =121a(3) =361a(4) =1352569a(5) =2140369a(6) =6416089a(7) =9186961a(8) =30261001a(9) =108056025a(10) =820765201a(11) =2331248089a(12) =170938421809