%I #13 Mar 24 2019 06:42:28

%S 0,4,6,14,26,54,104,210,412,832,1654,3330,6670,13452,27004,54414,

%T 109400,220264,442938,891256,1791894,3603128,7241452,14552628,

%U 29234478,58720290,117911510,236729446,475169660,953616548,1913446072,3838773120,7700145556,15443494464,30969376788,62096345834,124493833506

%N Number of length-n binary words that can be written as the concatenation of two unbordered binary words.

%C A word w is bordered if it has a nonempty prefix, unequal to w, that is also a suffix. A word is unbordered if it is not bordered.

%e For n = 5, the 6 words that are not so expressible are 00000, 00100, 01010, and their complements.

%Y Cf. A003000.

%K nonn

%O 1,2

%A _Jeffrey Shallit_, Mar 07 2019

%E a(23)-a(37) from _Bert Dobbelaere_, Mar 24 2019