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 A283512 #6 Nov 22 2017 01:15:07 %S A283512 2,11,212,2121,21211,121121,2212212,22122121,221221211,2212212112, %T A283512 22122121122,112212211211,1122122112112,11221221121121, %U A283512 112212211211212,1122122112112122,11211212212211211,112212211211212211,1211212212112212212,12112122121122122121,121121221211221221211 %N A283512 Last block of length-n to appear for the first time in the Kolakoski sequence K (A000002). %e A283512 For n = 4 the last block of length 4 to appear is 2121. %Y A283512 Cf. A000002, A007782, A283511. %K A283512 nonn %O A283512 1,1 %A A283512 _Jeffrey Shallit_, Mar 09 2017