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 A119128 #10 Mar 29 2023 05:02:08
%S A119128 1,114481,1188111,11841411,488184144441,8888818418481,114841884884181,
%T A119128 144118118141481,484118414411448411,141488881884888144481881,
%U A119128 148418181848481418444484488141,141848488814448448184488111481811,8114481418814448448488484488444141
%N A119128 Triangular numbers composed of digits {1,4,8}.
%C A119128 a(14) > 10^40. - _Tyler Busby_, Mar 28 2023
%H A119128 Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr148.html">Tridigital Triangular Numbers</a>.
%F A119128 a(n) = A000217(A119129(n)). - _Tyler Busby_, Mar 28 2023
%Y A119128 Cf. A000217, A053901, A119129. See A119033 for a table of cross-references.
%K A119128 nonn,base
%O A119128 1,2
%A A119128 _Giovanni Resta_, May 10 2006
%E A119128 a(12)-a(13) from _Max Alekseyev_, Aug 16 2013