Number of (n+2) X 6 0..2 matrices with each 3 X 3 subblock idempotent.

Terms

a(0) =416a(1) =449a(2) =571a(3) =666a(4) =906a(5) =1247a(6) =1657a(7) =2280a(8) =3216a(9) =4533a(10) =6443a(11) =9258a(12) =13358a(13) =19335a(14) =28093a(15) =40916a(16) =59680a(17) =87165a(18) =127435a(19) =186430a(20) =272870a(21) =399539a(22) =585161a(23) =857180a(24) =1255824a(25) =1840045a(26) =2696239a(27) =3951030a(28) =5789994a(29) =8485103