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 A053949 #25 Jul 18 2025 20:38:31
%S A053949 9,36,3969,69696,93636,3663396,9696996,966339396,6693366969,
%T A053949 36333696996,63396693369,96693633936,33993333636639339663936,
%U A053949 399339393339639693369636,9936969933633699966996996,396693636699939696999339663969,6636966336636339969666396999936,339666666363999366939366969366969936633336969
%N A053949 Squares composed of digits {3,6,9}.
%H A053949 Zhao Hui Du, <a href="/A053949/b053949.txt">Table of n, a(n) for n = 1..19</a>
%H A053949 Patrick De Geest, <a href="https://www.worldofnumbers.com/threedigits.htm">Squares containing at most three distinct digits, Index entries for related sequences</a>.
%H A053949 Hisanori Mishima, <a href="https://www.asahi-net.or.jp/~KC2H-MSM/mathland/math02/math0210.htm#369">Sporadic tridigital solutions</a>.
%H A053949 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>)
%F A053949 a(n) = A053948(n)^2. - _Elmo R. Oliveira_, Jul 18 2025
%Y A053949 Cf. A053948.
%K A053949 nonn,base
%O A053949 1,1
%A A053949 _Patrick De Geest_, Mar 15 2000
%E A053949 a(13)-a(14) from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 14 2005
%E A053949 a(15) from _Jon E. Schoenfield_, Sep 04 2006
%E A053949 a(16)-a(18) from Mishima's webpage added by _Max Alekseyev_, Jun 17 2011