Number of length-n binary words closed by an unbordered word.

Terms

a(0) =0a(1) =2a(2) =2a(3) =4a(4) =6a(5) =12a(6) =18a(7) =34a(8) =54a(9) =100a(10) =170a(11) =310a(12) =542a(13) =1000a(14) =1786a(15) =3292a(16) =5990a(17) =11100a(18) =20434a(19) =38102a(20) =70858a(21) =132912a(22) =249290a(23) =470300a(24) =888158a(25) =1684488a(26) =3199258a(27) =6095502a(28) =11631550a(29) =22249232