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 A053890 #34 Mar 07 2024 11:14:09
%S A053890 1,2,12,21,38,1188,20771,37962,3378512,11594538,65833989271,
%T A053890 3798830532038,575684923751188,21079405433537116521,
%U A053890 177324875114669443080086908188
%N A053890 Numbers k such that k^2 contains only digits {1,3,4}.
%H A053890 Author?, <a href="http://web.archive.org/web/20080708203024/http://blue.kakiko.com/mmrmmr/htm/eqtn06.html">Squares with at most three types of digits</a> (<a href="http://web.archive.org/web/20060426155831/http://blue.kakiko.com/mmrmmr/txt/eqtn06.txt">txt</a>)
%H A053890 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 A053890 H. Mishima, <a href="http://www.asahi-net.or.jp/~KC2H-MSM/mathland/math02/math0210.htm#134">Sporadic tridigital solutions</a>
%t A053890 Select[Range[1, 10000], ContainsOnly[IntegerDigits[#^2], {1, 3, 4}] &] (* _Julien Kluge_, Jul 08 2016 *)
%Y A053890 Cf. A053891.
%K A053890 nonn,base,more
%O A053890 1,2
%A A053890 _Patrick De Geest_, Mar 15 2000
%E A053890 More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 04 2005
%E A053890 One more term from _Jon E. Schoenfield_, Sep 03 2006
%E A053890 Two more terms from Mishima's page added by _Max Alekseyev_, Jan 28 2012
%E A053890 a(15) from _Zhao Hui Du_, Mar 06 2024