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 A239089 #16 Jun 09 2016 10:38:30 %S A239089 1,2,3,4,5,6,7,8,9,12,13,14,15,16,17,18,19,23,24,25,26,27,28,29,34,35, %T A239089 36,37,38,39,45,46,47,48,49,56,57,58,59,67,68,69,78,79,89,90,10,11,20, %U A239089 21,22,30,31,32,33,40,41,42,43,44,50 %N A239089 The sequence S = a(1), a(2), ... is defined by a(1)=1, if d,e,f are consecutive digits then we do not have d > e >= f, and S is always extended with the smallest integer not yet present in S. %C A239089 Computed by Lars Blomberg. %D A239089 Eric Angelini, Posting to Sequence Fans Mailing List, Sep 28 2013 %H A239089 Eric Angelini, <a href="http://www.cetteadressecomportecinquantesignes.com/LittleEqualGreat.htm">Less than <, Equal to =, Greater than ></a> (see sequence Sn) %H A239089 Eric Angelini, <a href="/A239083/a239083.pdf">Less than <, Equal to =, Greater than ></a> [Cached copy, with permission of the author] %Y A239089 The sequences in this family are given in A239083-A239086, A239136-A239139, A239087-A239090, A239215-A239218, A239235. %K A239089 nonn,base %O A239089 1,2 %A A239089 _N. J. A. Sloane_, Mar 11 2014