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 A241789 #15 Feb 17 2018 16:03:34
%S A241789 102378,103285,104653,106953,108345,109278,109746,120786,124750,
%T A241789 132870,135460,137026,138075,150426,152076,154290,158203,162735,
%U A241789 168490,170236,174936,178503,189420,190653,194376,197506,198765,203841,205761,215496,219453,231540
%N A241789 Triangular numbers which have one or more occurrences of exactly six different digits.
%C A241789 The first term having a repeated digit is 1004653.
%H A241789 Colin Barker, <a href="/A241789/b241789.txt">Table of n, a(n) for n = 1..2500</a>
%t A241789 Select[Table[(n(n+1))/2,{n,447,681}],Length[Union[ IntegerDigits[ #]]] == 6&] (* _Harvey P. Dale_, Feb 17 2018 *)
%o A241789 (PARI) s=[]; for(n=0, 800, if(#vecsort(eval(Vec(Str(n*(n+1)/2))), , 8)==6, s=concat(s, n*(n+1)/2))); s
%Y A241789 Cf. A045914, A062691, A162304, A241787, A241788, A241790, A241791, A241792, A241812.
%Y A241789 Cf. A000217.
%K A241789 nonn,base
%O A241789 1,1
%A A241789 _Colin Barker_, Apr 28 2014