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 A028440 #4 Mar 30 2012 17:20:44 %S A028440 10,20,30,40,50,60,70,80,90,101,111,121,131,141,151,161,171,181,191, %T A028440 201,211,221,231,241,251,261,271,281,291,301,311,321,331,341,351,361, %U A028440 371,381,391,401,411,421,431,441,451,461,471,481,491,501,511,521,531 %N A028440 Golc sequence in base 10. Left to right concatenation of n,int(log_10(n)),int(log_10(int(log_10(n)))),... in base 10. %K A028440 nonn,base,easy %O A028440 1,1 %A A028440 _Olivier Gérard_