Number of binary words of length n in which the ones occur only in blocks of length at least 4.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =4a(6) =7a(7) =11a(8) =16a(9) =23a(10) =34a(11) =52a(12) =81a(13) =126a(14) =194a(15) =296a(16) =450a(17) =685a(18) =1046a(19) =1601a(20) =2452a(21) =3753a(22) =5739a(23) =8771a(24) =13404a(25) =20489a(26) =31327a(27) =47904a(28) =73252a(29) =112004