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 A119064 #9 Jul 13 2021 01:20:32
%S A119064 2,3,8,11,24,35,36,77,363,816,1095,1122,2571,7788,25704,114920,
%T A119064 11281016,35599539,355057836,11489128191,258315170402,852060600000,
%U A119064 1151781516003,3559869761679,25703436746877,25704497685660
%N A119064 Numbers k such that the k-th triangular number contains only digits {0,3,6}.
%H A119064 G. Resta, <a href="http://www.numbersaplenty.com/tr/tr036.html">Tridigital Triangular Numbers</a>
%Y A119064 Cf. A000217, A119063. See A119034 for a table of cross-references.
%K A119064 nonn,base
%O A119064 1,1
%A A119064 _Giovanni Resta_, May 10 2006