Number of 4 X n 0..1 arrays avoiding 0 0 1 and 0 1 1 horizontally and 0 0 1 and 1 0 0 vertically.

Terms

a(0) =9a(1) =81a(2) =270a(3) =900a(4) =2100a(5) =4900a(6) =9450a(7) =18225a(8) =31185a(9) =53361a(10) =84084a(11) =132496a(12) =196560a(13) =291600a(14) =413100a(15) =585225a(16) =799425a(17) =1092025a(18) =1448370a(19) =1920996a(20) =2486484a(21) =3218436a(22) =4081350a(23) =5175625a(24) =6449625a(25) =8037225a(26) =9865800a(27) =12110400a(28) =14671680a(29) =17774656