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 A119167 #12 Mar 31 2023 02:43:13
%S A119167 10,74,714,1074,1070285,2270474,1206047449,67189697949,324723752049,
%T A119167 23346424812260967349
%N A119167 Numbers k such that the k-th triangular number contains only digits {2,5,7}.
%H A119167 Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr257.html">Tridigital Triangular Numbers</a>.
%Y A119167 Cf. A000217, A119166. See A119034 for a table of cross-references.
%K A119167 nonn,base,more
%O A119167 1,1
%A A119167 _Giovanni Resta_, May 10 2006
%E A119167 a(10) from _Tyler Busby_, Mar 31 2023