Number of binary strings of length n containing the substring 11011.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =1a(6) =4a(7) =12a(8) =31a(9) =75a(10) =175a(11) =399a(12) =894a(13) =1975a(14) =4313a(15) =9330a(16) =20026a(17) =42704a(18) =90558a(19) =191117a(20) =401654a(21) =841016a(22) =1755249a(23) =3652663a(24) =7581369a(25) =15698735a(26) =32438224a(27) =66897295a(28) =137718495a(29) =283056086