Number of binary necklaces of length n with no subsequence 0000.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =6a(5) =11a(6) =15a(7) =27a(8) =43a(9) =75a(10) =125a(11) =228a(12) =391a(13) =707a(14) =1262a(15) =2285a(16) =4119a(17) =7525a(18) =13691a(19) =25111a(20) =46033a(21) =84740a(22) =156123a(23) =288529a(24) =533670a(25) =989305a(26) =1835983a(27) =3412885a(28) =6351031a(29) =11834623