Number of (n+2) X 6 0..1 matrices with each 3 X 3 subblock idempotent.

Terms

a(0) =172a(1) =174a(2) =230a(3) =286a(4) =395a(5) =551a(6) =749a(7) =1041a(8) =1473a(9) =2086a(10) =2973a(11) =4273a(12) =6166a(13) =8925a(14) =12962a(15) =18869a(16) =27511a(17) =40165a(18) =58700a(19) =85850a(20) =125626a(21) =183908a(22) =269310a(23) =394457a(24) =577854a(25) =846620a(26) =1240499a(27) =1817740a(28) =2663711a(29) =3903524