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 A119235 #9 Jul 13 2021 21:31:04
%S A119235 3,11,36,371211,421186108,1180677745929588
%N A119235 Numbers k such that the k-th triangular number contains only digits {6,8,9}.
%C A119235 Next term exceeds 4.4*10^18.
%H A119235 G. Resta, <a href="http://www.numbersaplenty.com/tr/tr689.html">Tridigital Triangular Numbers</a>
%Y A119235 Cf. A000217, A119234. See A119034 for a table of cross-references.
%K A119235 nonn,base,more
%O A119235 1,1
%A A119235 _Giovanni Resta_, May 10 2006
%E A119235 Lower bound updated by _Max Alekseyev_, Apr 30 2010