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 A006920 M2126 #17 Oct 08 2022 14:15:50 %S A006920 1,1,2,21,32,331,433,4351,53621,647221,7673221,8883233,891132333, %T A006920 8101532334101,101118423351110001,141220533351220001001, %U A006920 17142355335122101100101,23162558335122102101101001,30192751033612210211110100201,3823295114361321021111110020101001 %N A006920 At each step, record how many 1's, 2's, etc. have been seen so far in the sequence. %D A006920 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %Y A006920 A333867 is the tabular version of this sequence. %K A006920 nonn,base %O A006920 1,3 %A A006920 _N. J. A. Sloane_, _James Propp_ %E A006920 More terms from _Franklin T. Adams-Watters_, Dec 14 2006