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 A119189 #10 Mar 31 2023 02:49:27
%S A119189 2,10,3386897,10367022,25898098514,33868444120607410,
%T A119189 3835970218282143377
%N A119189 Numbers k such that the k-th triangular number contains only digits {3,5,7}.
%H A119189 Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr357.html">Tridigital Triangular Numbers</a>.
%Y A119189 Cf. A000217, A119188. See A119034 for a table of cross-references.
%K A119189 nonn,base,more
%O A119189 1,1
%A A119189 _Giovanni Resta_, May 10 2006
%E A119189 a(6)-a(7) from _Tyler Busby_, Mar 31 2023