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 A048708 #12 Oct 10 2022 11:09:03 %S A048708 0,1,6,69,6996,69969669,6996966996696996, %T A048708 69969669966969969669699669969669, %U A048708 6996966996696996966969966996966996696996699696696996966996696996 %N A048708 Numerators of ratios converging to the Thue-Morse constant, converted to hexadecimal. %C A048708 Starting from the term 6, the next term can be obtained from the previous one by appending its "horizontally" flipped variant (6 <-> 9, which equals its binary complement). Also, starting from the term 69, every second term stays same if read upside down from the other end (i.e., those numbers look same even if you rotate them by 180 degrees). %F A048708 map(convert, A048707, hex) %Y A048708 Cf. A048705, A048706, A048707. %K A048708 nonn,base %O A048708 0,3 %A A048708 _Antti Karttunen_, Mar 09 1999