This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A332983 #6 Mar 05 2020 22:51:29 %S A332983 0,2,2,4,6,12,18,34,54,100,170,310,542,1000,1786,3292,5990,11100, %T A332983 20434,38102,70858,132912,249290,470300,888158,1684488,3199258, %U A332983 6095502,11631550,22249232,42621834,81804946,157221374,302632804,583237734,1125468466,2174144774 %N A332983 Number of length-n binary words closed by an unbordered word. %C A332983 A word is unbordered if it has no nontrivial prefix that is a suffix. A word x is closed by a word y if y has exactly two occurrences in x, one as a prefix, and one as a suffix. %e A332983 For n = 5 the a(5) = 6 words counted are 01001, 01101, 01110, and their binary complements. %Y A332983 Counts a subset of A226452. %K A332983 nonn %O A332983 1,2 %A A332983 _Jeffrey Shallit_, Mar 05 2020