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 A119155 #8 Jul 13 2021 07:26:55
%S A119155 2,3,8,11,36,211,816,6816,25948,66816,80791,111948,724323,730251,
%T A119155 2127563,8511948,364234436,80456475963,81513466816,2159924381188,
%U A119155 2554314912583,3651400351272436
%N A119155 Numbers k such that the k-th triangular number contains only digits {2,3,6}.
%C A119155 Next term exceeds 1.4*10^16.
%H A119155 G. Resta, <a href="http://www.numbersaplenty.com/tr/tr236.html">Tridigital Triangular Numbers</a>
%Y A119155 Cf. A000217, A119154. See A119034 for a table of cross-references.
%K A119155 nonn,base,more
%O A119155 1,1
%A A119155 _Giovanni Resta_, May 10 2006