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 A119038 #16 Sep 08 2022 08:45:25
%S A119038 1,4,141,144,286,9055,16795,44944,90598,167579,15100424,29678424,
%T A119038 45637726,283245880,5291767266,1442505046119,45042455839799,
%U A119038 151069595909375,14429213707617199,90999011435291333
%N A119038 Numbers k such that the k-th triangular number contains only digits {0,1,4}.
%C A119038 Next term must be greater than 4.4*10^18.
%H A119038 G. Resta, <a href="http://www.numbersaplenty.com/tr/tr014.html">Tridigital Triangular Numbers</a>
%t A119038 Select[Range[2 10^7], Complement[IntegerDigits[Binomial[# + 1, 2]], {0, 1, 4}] == {}&] (* _Vincenzo Librandi_, Oct 07 2015 *)
%o A119038 (Magma) [n: n in [1..2*10^7] | Set(Intseq(Binomial(n+1, 2))) subset [0, 1, 4]]; // _Vincenzo Librandi_, Oct 07 2015
%Y A119038 Cf. A000217, A119037. See A119034 for a table of cross-references.
%K A119038 nonn,base
%O A119038 1,2
%A A119038 _Giovanni Resta_, May 10 2006
%E A119038 Two more terms from _Max Alekseyev_, Jul 11 2009