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 A119175 #8 Jul 13 2021 07:23:24
%S A119175 3,7,11,36,72,676,1287,2108,11512,21112,23927,35447,37112,41527,67323,
%T A119175 35289847,41633847,11684368072,24026103588,364110500487,
%U A119175 7566093164465563
%N A119175 Numbers k such that the k-th triangular number contains only digits {2,6,8}.
%C A119175 Next term exceeds 1.4*10^16.
%H A119175 G. Resta, <a href="http://www.numbersaplenty.com/tr/tr268.html">Tridigital Triangular Numbers</a>
%Y A119175 Cf. A000217, A119174. See A119034 for a table of cross-references.
%K A119175 nonn,base,more
%O A119175 1,1
%A A119175 _Giovanni Resta_, May 10 2006