Number of quasi-triominoes in an n X n bounding box.

Terms

a(0) =0a(1) =0a(2) =1a(3) =10a(4) =33a(5) =88a(6) =187a(7) =360a(8) =625a(9) =1024a(10) =1581a(11) =2350a(12) =3361a(13) =4680a(14) =6343a(15) =8428a(16) =10977a(17) =14080a(18) =17785a(19) =22194a(20) =27361a(21) =33400a(22) =40371a(23) =48400a(24) =57553a(25) =67968a(26) =79717a(27) =92950a(28) =107745a(29) =124264