Quarter-squares repeated.

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =4a(5) =4a(6) =6a(7) =6a(8) =9a(9) =9a(10) =12a(11) =12a(12) =16a(13) =16a(14) =20a(15) =20a(16) =25a(17) =25a(18) =30a(19) =30a(20) =36a(21) =36a(22) =42a(23) =42a(24) =49a(25) =49a(26) =56a(27) =56a(28) =64a(29) =64