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 A108685 #10 Nov 26 2020 16:41:10 %S A108685 0,10,21,30,42,51,63,70,84,92,105,111,126,133,147,150,168,174,189,192, %T A108685 2010,2152,2112,3124,12256,26132,73281,429730,1531032,1633834,1735436, %U A108685 1837938,1939240,2041104,2214354,4224511 %N A108685 Hidden fractal sequence: increasing sequence all of whose successive digits are the digits of the fractal sequence A025480 (which is built upon the natural counting numbers). %H A108685 Clark Kimberling, <a href="http://faculty.evansville.edu/ck6/integer/fractals.html">fractal sequences</a>. %Y A108685 Cf. A003602, A025480, A108202. %K A108685 base,easy,nonn %O A108685 0,2 %A A108685 _Alexandre Wajnberg_, Jun 18 2005