Rhombic numbers.

Terms

a(0) =3a(1) =7a(2) =8a(3) =11a(4) =15a(5) =19a(6) =23a(7) =24a(8) =27a(9) =31a(10) =32a(11) =35a(12) =40a(13) =43a(14) =47a(15) =48a(16) =51a(17) =59a(18) =63a(19) =67a(20) =71a(21) =75a(22) =79a(23) =80a(24) =83a(25) =87a(26) =88a(27) =91a(28) =96a(29) =99