Numbers of the form x^2 + xy + y^2, where x and y are positive integers.

Terms

a(0) =3a(1) =7a(2) =12a(3) =13a(4) =19a(5) =21a(6) =27a(7) =28a(8) =31a(9) =37a(10) =39a(11) =43a(12) =48a(13) =49a(14) =52a(15) =57a(16) =61a(17) =63a(18) =67a(19) =73a(20) =75a(21) =76a(22) =79a(23) =84a(24) =91a(25) =93a(26) =97a(27) =103a(28) =108a(29) =109