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 A053911 #15 Jul 16 2025 13:41:47
%S A053911 1,9,16,169,196,961,69169,69696,9696996,16966161,611919169,6661661161,
%T A053911 696199996996,1911961611169,99191919116196,116116119966961,
%U A053911 116696699999166169,699666116199699961,996111661161199969,611961619961911196961,1616161166196691196196,9919969966699691196169
%N A053911 Squares composed of digits {1,6,9}.
%H A053911 Zhao Hui Du, <a href="/A053911/b053911.txt">Table of n, a(n) for n = 1..31</a>
%H A053911 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 A053911 Hisanori Mishima, <a href="https://www.asahi-net.or.jp/~KC2H-MSM/mathland/math02/math0210.htm#169">Sporadic tridigital solutions</a>.
%F A053911 a(n) = A053910(n)^2. - _Elmo R. Oliveira_, Jul 16 2025
%Y A053911 Cf. A053910.
%K A053911 nonn,base
%O A053911 1,2
%A A053911 _Patrick De Geest_, Mar 15 2000