Number of (n+2) X 9 0..1 matrices with each 3 X 3 subblock idempotent.

Terms

a(0) =669a(1) =492a(2) =620a(3) =749a(4) =988a(5) =1298a(6) =1668a(7) =2201a(8) =2961a(9) =4001a(10) =5477a(11) =7609a(12) =10670a(13) =15089a(14) =21515a(15) =30870a(16) =44505a(17) =64420a(18) =93537a(19) =136129a(20) =198469a(21) =289752a(22) =423446a(23) =619292a(24) =906226a(25) =1326652a(26) =1942715a(27) =2845496a(28) =4168480a(29) =6107297