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 A119161 #11 Jul 13 2021 07:26:00
%S A119161 3,11,36,923,23076,211963,9656548,35906663076,9635790203866668,
%T A119161 35401826004387588
%N A119161 Numbers k such that the k-th triangular number contains only digits {2,4,6}.
%C A119161 Next term exceeds 3.1*10^18.
%H A119161 G. Resta, <a href="http://www.numbersaplenty.com/tr/tr246.html">Tridigital Triangular Numbers</a>
%Y A119161 Cf. A000217, A119160. See A119034 for a table of cross-references.
%K A119161 nonn,base,more
%O A119161 1,1
%A A119161 _Giovanni Resta_, May 10 2006
%E A119161 a(10) from _Max Alekseyev_, Jun 16 2011