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 A213976 #3 Jul 05 2012 10:37:52 %S A213976 2,1,21,121,21121,12121121,2112112121121,121211212112112121121, %T A213976 2112112121121121211212112112121121, %U A213976 1212112121121121211212112112121121121211212112112121121,21121121211211212112121121121211211212112121121121211212112112121121121211212112112121121 %N A213976 a(n) = n-th term of A106750 reversed. %C A213976 Arises in analyzing factors of A003842. %H A213976 M. Lothaire, <a href="http://www-igm.univ-mlv.fr/~berstel/Lothaire/">Algebraic Combinatorics on Words</a>, Cambridge, 2002 %Y A213976 Cf. A003842, A106750, A213975. %K A213976 nonn %O A213976 0,1 %A A213976 _N. J. A. Sloane_, Jul 05 2012