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 A119229 #11 Mar 31 2023 05:15:38
%S A119229 10,34,109,1054,13114114,105440870,1340887434,33454026929,44472235965,
%T A119229 13106479203810,3345411351684270,131072391368959890,421873345684598945
%N A119229 Numbers k such that the k-th triangular number contains only digits {5,8,9}.
%H A119229 Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr589.html">Tridigital Triangular Numbers</a>.
%Y A119229 Cf. A000217, A119228. See A119034 for a table of cross-references.
%K A119229 nonn,base,more
%O A119229 1,1
%A A119229 _Giovanni Resta_, May 10 2006
%E A119229 a(12)-a(13) from _Tyler Busby_, Mar 31 2023