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

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =14a(5) =25a(6) =45a(7) =80a(8) =142a(9) =253a(10) =450a(11) =800a(12) =1423a(13) =2531a(14) =4501a(15) =8005a(16) =14237a(17) =25320a(18) =45031a(19) =80087a(20) =142433a(21) =253314a(22) =450514a(23) =801230a(24) =1424971a(25) =2534282a(26) =4507169a(27) =8015908a(28) =14256129a(29) =25354235