Number of nX4 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 1 1 vertically.

Terms

a(0) =9a(1) =81a(2) =166a(3) =438a(4) =1042a(5) =1992a(6) =4168a(7) =8174a(8) =15881a(9) =30801a(10) =58335a(11) =111083a(12) =209072a(13) =391336a(14) =731541a(15) =1358864a(16) =2519079a(17) =4655423a(18) =8579122a(19) =15779179a(20) =28954160a(21) =53037211a(22) =96982948a(23) =177063128a(24) =322816525a(25) =587759306a(26) =1068885187a(27) =1941639552a(28) =3523372673