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 A285211 #20 Jul 14 2021 10:04:29
%S A285211 2,3,4,6,7,8,9,10,11,12,24,26,28,29,30,31,33,34,38,39,42,44,46,47,48,
%T A285211 49,52,58,59,62,64,66,69,70,71,77,79,82,84,86,88,89,114,115,117,122,
%U A285211 124,129,131,132,246,252,258,259,262,266,270,271,277,282,286
%N A285211 Numbers k that share no digits with the k-th triangular number.
%H A285211 Robert Israel, <a href="/A285211/b285211.txt">Table of n, a(n) for n = 1..6434</a>
%p A285211 filter:= proc(n) convert(convert(n,base,10),set) intersect convert(convert(n*(n+1)/2,base,10),set) = {} end proc:
%p A285211 select(filter, [$1..1000]); # _Robert Israel_, Apr 21 2017
%o A285211 (PARI) L=List(); for(n=1, 500, if(setintersect(vecsort(digits(n),,8), vecsort(digits(n*(n+1)/2),,8))==[], listput(L, n))); Vec(L)
%Y A285211 Cf. A000217, A029783.
%K A285211 nonn,base
%O A285211 1,1
%A A285211 _Colin Barker_, Apr 13 2017