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 A340503 #5 Jan 17 2021 16:42:46 %S A340503 0,2,0,1,0,2,3,2,0,2,0,1,3,1,0,1,0,2,0,1,0,2,3,2,3,1,3,2,0,2,3,2,0,2, %T A340503 0,1,0,2,3,2,0,2,0,1,3,1,0,1,3,1,3,2,3,1,0,1,0,2,0,1,3,1,0,1,0,2,0,1, %U A340503 0,2,3,2,0,2,0,1,3,1,0,1,0,2,0,1,0,2,3,2,3,1,3,2,0,2,3,2,3,1,3,2,3,1,0,1,3 %N A340503 Fixed under 0 -> 02, 1 -> 32, 2 -> 01, 3 -> 31. %C A340503 Yet another version of the Rudin-Shapiro sequence A020987. %D A340503 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 1.7. %Y A340503 Cf. A020985, A020987, A100260, A340504. %K A340503 nonn %O A340503 1,2 %A A340503 _N. J. A. Sloane_, Jan 17 2021