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 A077209 #6 Jan 08 2019 09:12:41 %S A077209 2,21,101,102,201,1001,1002,2001,10001,10002,20001,100001,100002, %T A077209 200001,1000001,1000002,2000001,10000001,10000002,20000001,100000001, %U A077209 100000002,200000001 %N A077209 a(1) = 2, then the smallest squarefree number greater than the previous term that begins with the end of the previous term. %C A077209 Are there terms using digits greater than 2? %Y A077209 Cf. A077208. %K A077209 base,nonn %O A077209 0,1 %A A077209 _Amarnath Murthy_, Nov 02 2002 %E A077209 More terms from _Michel ten Voorde_ Jun 13 2003