Number of (n+2) X 4 0..1 matrices with each 3 X 3 subblock idempotent.

Terms

a(0) =70a(1) =94a(2) =133a(3) =174a(4) =246a(5) =351a(6) =492a(7) =693a(8) =992a(9) =1418a(10) =2036a(11) =2937a(12) =4253a(13) =6169a(14) =8973a(15) =13073a(16) =19074a(17) =27857a(18) =40723a(19) =59566a(20) =87173a(21) =127620a(22) =186889a(23) =273737a(24) =401009a(25) =587520a(26) =860854a(27) =1261428a(28) =1848486a(29) =2708844