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 A119083 #8 Mar 28 2023 08:00:55
%S A119083 55,5050,500500,50005000,5000050000,500000500000,558080805855,
%T A119083 50000005000000,808505508008850,5000000050000000,500000000500000000,
%U A119083 50000000005000000000,5000000000050000000000,5055055888880005805800,500000000000500000000000
%N A119083 Triangular numbers composed of digits {0,5,8}.
%H A119083 Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr058.html">Tridigital Triangular Numbers</a>.
%F A119083 a(n) = A000217(A119084(n)). - _Tyler Busby_, Mar 27 2023
%Y A119083 Cf. A000217, A119084. See A119033 for a table of cross-references.
%K A119083 nonn,base
%O A119083 1,1
%A A119083 _Giovanni Resta_, May 10 2006
%E A119083 a(15) from _Tyler Busby_, Mar 27 2023