Number of nX3 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 0 and 0 1 1 vertically.

Terms

a(0) =6a(1) =36a(2) =102a(3) =261a(4) =611a(5) =1278a(6) =2625a(7) =5134a(8) =9798a(9) =18414a(10) =33947a(11) =62049a(12) =112332a(13) =201925a(14) =361298a(15) =643452a(16) =1142526a(17) =2023513a(18) =3576387a(19) =6311690a(20) =11124765a(21) =19589642a(22) =34469830a(23) =60616350a(24) =106548039a(25) =187215857a(26) =328865096a(27) =577561897a(28) =1014154398