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 A340504 #7 Jan 17 2021 16:45:16 %S A340504 0,3,0,1,0,3,2,3,0,3,0,1,2,1,0,1,0,3,0,1,0,3,2,3,2,1,2,3,0,3,2,3,0,3, %T A340504 0,1,0,3,2,3,0,3,0,1,2,1,0,1,2,1,2,3,2,1,0,1,0,3,0,1,2,1,0,1,0,3,0,1, %U A340504 0,3,2,3,0,3,0,1,2,1,0,1,0,3,0,1,0,3,2,3,2,1,2,3,0,3,2,3,2,1,2,3,2,1,0,1,2 %N A340504 Fixed under 0 -> 03, 1 -> 23, 2 -> 21, 3 -> 01. %C A340504 Yet another version of the Rudin-Shapiro sequence A020987. %D A340504 Dekking, Michel, Michel Mendes France, and Alf van der Poorten. "Folds." The Mathematical Intelligencer, 4.3 (1982): 130-138 & front cover, and 4:4 (1982): 173-181 (printed in two parts). See Observation 1.17. %Y A340504 Cf. A020985, A020987, A100260, A340503. %K A340504 nonn %O A340504 1,2 %A A340504 _N. J. A. Sloane_, Jan 17 2021