Number of (n+3)X(n+3) 0..1 matrices with each 4X4 subblock idempotent.

Terms

a(0) =452a(1) =340a(2) =514a(3) =752a(4) =974a(5) =1550a(6) =2526a(7) =3918a(8) =5716a(9) =8536a(10) =12978a(11) =19670a(12) =29226a(13) =43204a(14) =63992a(15) =94856a(16) =139914a(17) =205488a(18) =301196a(19) =441124a(20) =644948a(21) =940908a(22) =1370156a(23) =1992618a(24) =2894276a(25) =4198330a(26) =6081892a(27) =8800132a(28) =12719614a(29) =18365760