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 A119050 #13 Sep 08 2022 08:45:25
%S A119050 2,24,77,215,637,802,8002,25815,80002,800002,2158797,8000002,25768322,
%T A119050 66382562,80000002,800000002,8000000002,21596311362,80000000002,
%U A119050 800000000002,8000000000002,80000000000002,800000000000002
%N A119050 Numbers k such that the k-th triangular number contains only digits {0,2,3}.
%H A119050 G. Resta, <a href="http://www.numbersaplenty.com/tr/tr023.html">Tridigital Triangular Numbers</a>
%t A119050 Select[Range[3 10^7], Complement[IntegerDigits[Binomial[# + 1, 2]], {0, 2, 3}] == {}&] (* _Vincenzo Librandi_,Oct 07 2015 *)
%o A119050 (Magma) [n: n in [1..2*10^7] | Set(Intseq(Binomial(n+1, 2))) subset [0, 2, 3]]; // _Vincenzo Librandi_, Oct 07 2015
%Y A119050 Cf. A000217, A119049. See A119034 for a table of cross-references.
%K A119050 nonn,base
%O A119050 1,1
%A A119050 _Giovanni Resta_, May 10 2006