Number of binary strings of length n with no substrings equal to 0001 or 1100.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =14a(5) =24a(6) =41a(7) =70a(8) =120a(9) =206a(10) =354a(11) =609a(12) =1048a(13) =1804a(14) =3106a(15) =5348a(16) =9209a(17) =15858a(18) =27308a(19) =47026a(20) =80982a(21) =139457a(22) =240156a(23) =413568a(24) =712198a(25) =1226464a(26) =2112073a(27) =3637166a(28) =6263504a(29) =10786278