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 A119055 #11 Mar 31 2023 14:12:56
%S A119055 28,820,2080,80200,200028,828828,8002000,800020000,8028028828,
%T A119055 22002880200,80000200000,208808222028,220028220028,8000002000000,
%U A119055 800000020000000,2880222880828800,22822222802022028,80000000200000000,8000000002000000000,80820888088020828828
%N A119055 Triangular numbers composed of digits {0,2,8}.
%H A119055 Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr028.html">Tridigital Triangular Numbers</a>.
%F A119055 a(n) = A000217(A119056(n)). - _Tyler Busby_, Mar 31 2023
%Y A119055 Cf. A000217, A119056. See A119033 for a table of cross-references.
%K A119055 nonn,base
%O A119055 1,1
%A A119055 _Giovanni Resta_, May 10 2006
%E A119055 a(19)-a(20) from _Tyler Busby_, Mar 22 2023