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 A119108 #8 Jul 13 2021 01:24:51
%S A119108 1,6,7,47,66,127,487,666,1281,1287,1327,1541,1912,6666,7512,13327,
%T A119108 60352,66666,133327,666666,1333327,6666666,13333327,47375333,66666666,
%U A119108 133333327,666666666,1333333327,6666666666,12750044793,13333333327
%N A119108 Numbers k such that the k-th triangular number contains only digits {1,2,8}.
%H A119108 G. Resta, <a href="http://www.numbersaplenty.com/tr/tr128.html">Tridigital Triangular Numbers</a>
%Y A119108 Cf. A000217, A119107. See A119034 for a table of cross-references.
%K A119108 nonn,base
%O A119108 1,2
%A A119108 _Giovanni Resta_, May 10 2006