Rhombi (in 3 different orientations) in a rhombus with 60-degree acute angles.

Terms

a(0) =1a(1) =9a(2) =26a(3) =54a(4) =95a(5) =151a(6) =224a(7) =316a(8) =429a(9) =565a(10) =726a(11) =914a(12) =1131a(13) =1379a(14) =1660a(15) =1976a(16) =2329a(17) =2721a(18) =3154a(19) =3630a(20) =4151a(21) =4719a(22) =5336a(23) =6004a(24) =6725a(25) =7501a(26) =8334a(27) =9226a(28) =10179a(29) =11195