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 A119190 #11 Apr 06 2023 21:42:06
%S A119190 3,55,8385,353833535835,338385588883835583555,
%T A119190 5838535388555338533383385,55335355335583353383833585
%N A119190 Triangular numbers composed of digits {3,5,8}.
%C A119190 a(8) > 10^40. - _Tyler Busby_, Mar 29 2023
%H A119190 Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr358.html">Tridigital Triangular Numbers</a>.
%F A119190 a(n) = A000217(A119191(n)). - _Tyler Busby_, Mar 29 2023
%Y A119190 Cf. A000217, A119191. See A119033 for a table of cross-references.
%K A119190 nonn,base,more
%O A119190 1,1
%A A119190 _Giovanni Resta_, May 10 2006