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

Terms

a(0) =9a(1) =81a(2) =261a(3) =603a(4) =1161a(5) =1989a(6) =3141a(7) =4671a(8) =6633a(9) =9081a(10) =12069a(11) =15651a(12) =19881a(13) =24813a(14) =30501a(15) =36999a(16) =44361a(17) =52641a(18) =61893a(19) =72171a(20) =83529a(21) =96021a(22) =109701a(23) =124623a(24) =140841a(25) =158409a(26) =177381a(27) =197811a(28) =219753a(29) =243261