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 A119049 #10 Mar 14 2023 16:09:04
%S A119049 3,300,3003,23220,203203,322003,32020003,333220020,3200200003,
%T A119049 320002000003,2330203323003,32000020000003,332003222232003,
%U A119049 2203322302033203,3200000200000003,320000002000000003,32000000020000000003,233200332233023303203,3200000000200000000003
%N A119049 Triangular numbers composed of digits {0,2,3}.
%H A119049 Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr023.html">Tridigital Triangular Numbers</a>
%F A119049 a(n) = A000217(A119050(n)). - _Michel Marcus_, Mar 14 2023
%Y A119049 Cf. A000217, A119050. See A119033 for a table of cross-references.
%K A119049 nonn,base
%O A119049 1,1
%A A119049 _Giovanni Resta_, May 10 2006
%E A119049 a(17)-a(19) from _Tyler Busby_, Mar 14 2023