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 A053891 #19 Mar 11 2024 08:20:00
%S A053891 1,4,144,441,1444,1411344,431434441,1441113444,11414343334144,
%T A053891 134433311433444,4334114143334143111441,14431113411144114144433444,
%U A053891 331413131434411141441331411344,444341333431434111311131411343131143441
%N A053891 Squares composed of digits {1,3,4}.
%H A053891 Zhao Hui Du, <a href="/A053891/b053891.txt">Table of n, a(n) for n = 1..15</a>
%H A053891 Author?, <a href="http://web.archive.org/web/20080708203024/http://blue.kakiko.com/mmrmmr/htm/eqtn06.html">Source</a>(<a href="http://web.archive.org/web/20060426155831/http://blue.kakiko.com/mmrmmr/txt/eqtn06.txt">txt</a>)
%H A053891 Patrick De Geest, <a href="http://www.worldofnumbers.com/threedigits.htm">Squares containing at most three distinct digits, Index entries for related sequences</a>
%H A053891 H. Mishima, <a href="http://www.asahi-net.or.jp/~KC2H-MSM/mathland/math02/math0210.htm#134">Sporadic tridigital solutions</a>
%F A053891 a(n) = A053890(n)^2.
%Y A053891 Cf. A053890.
%K A053891 nonn,base
%O A053891 1,2
%A A053891 _Patrick De Geest_, Mar 15 2000
%E A053891 More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 04 2005
%E A053891 One more term from _Jon E. Schoenfield_, Sep 03 2006
%E A053891 Two more terms from Mishima's page added by _Max Alekseyev_, Jan 28 2012