Number of binary strings of length n with no substrings equal to 0000, 0011, or 1001.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =13a(5) =22a(6) =37a(7) =62a(8) =104a(9) =175a(10) =294a(11) =494a(12) =830a(13) =1395a(14) =2344a(15) =3939a(16) =6619a(17) =11123a(18) =18691a(19) =31409a(20) =52780a(21) =88693a(22) =149041a(23) =250452a(24) =420864a(25) =707229a(26) =1188441a(27) =1997081a(28) =3355934a(29) =5639380