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 A119181 #8 Jul 13 2021 07:24:19
%S A119181 7,1287,4312,14087,75934087,421883687,773669476312
%N A119181 Numbers k such that the k-th triangular number contains only digits {2,8,9}.
%C A119181 Next term exceeds 1.4*10^16.
%H A119181 G. Resta, <a href="http://www.numbersaplenty.com/tr/tr289.html">Tridigital Triangular Numbers</a>
%Y A119181 Cf. A000217, A119180. See A119034 for a table of cross-references.
%K A119181 nonn,base,more
%O A119181 1,1
%A A119181 _Giovanni Resta_, May 10 2006