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 A215330 #12 Jun 17 2019 07:30:45 %S A215330 1,4,3,8,18,47,108,268,638,1553,3761,9189,22453,55185,135894,335906, %T A215330 832312,2068066,5149845,12852750,32138353,80509495,202013368, %U A215330 507669048,1277586867,3219366610,8122275225 %N A215330 Smooth Lyndon words with 4 colors. %C A215330 We call a Lyndon word (x[1],x[2],...,x[n]) smooth if abs(x[k]-x[k-1]) <= 1 for 2<=k<=n. %e A215330 (See A215329). %Y A215330 Cf. A215329 (smooth necklaces, 4 colors), A215328 (smooth Lyndon words, 3 colors). %K A215330 nonn,more %O A215330 0,2 %A A215330 _Joerg Arndt_, Aug 08 2012 %E A215330 More terms from _Joerg Arndt_, Jun 17 2019