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

Terms

a(0) =41a(1) =76a(2) =108a(3) =170a(4) =257a(5) =398a(6) =617a(7) =967a(8) =1525a(9) =2421a(10) =3862a(11) =6185a(12) =9934a(13) =15990a(14) =25778a(15) =41604a(16) =67199a(17) =108600a(18) =175575a(19) =283929a(20) =459235a(21) =742871a(22) =1201788a(23) =1944315a(24) =3145732a(25) =5089648a(26) =8234952a(27) =13324142a(28) =21558605a(29) =34882226