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 A119214 #12 Mar 29 2023 17:51:33
%S A119214 6,66,496,666,946,4699966666944446964496
%N A119214 Triangular numbers composed of digits {4,6,9}.
%C A119214 a(7) > 10^40. - _Tyler Busby_, Mar 29 2023
%H A119214 Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr469.html">Tridigital Triangular Numbers</a>.
%F A119214 a(n) = A000217(A119215(n)). - _Michel Marcus_, Mar 27 2023
%Y A119214 Cf. A000217, A053961, A119215. See A119033 for a table of cross-references.
%K A119214 nonn,base,more
%O A119214 1,1
%A A119214 _Giovanni Resta_, May 10 2006