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 A053898 #23 Aug 11 2024 14:41:32
%S A053898 1,2,12,21,38,88,2729,2036462,2678521,1203108962,343143082067979,
%T A053898 2678520388463521,1071033028175028538,2177492084289725902412
%N A053898 Numbers k such that k^2 contains only digits {1,4,7}.
%H A053898 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>) [Broken link]
%H A053898 P. De Geest, <a href="https://www.worldofnumbers.com/threedigits.htm">Squares containing at most three distinct digits, Index entries for related sequences</a>
%H A053898 H. Mishima, <a href="http://www.asahi-net.or.jp/~KC2H-MSM/mathland/math02/math0210.htm#147">Sporadic tridigital solutions</a>
%t A053898 Select[Range[1, 10000],ContainsOnly[IntegerDigits[#^2], {1, 4, 7}] &] (* _Julien Kluge_, Jul 08 2016 *)
%Y A053898 Cf. A053899.
%K A053898 nonn,base,more
%O A053898 1,2
%A A053898 _Patrick De Geest_, Mar 15 2000
%E A053898 More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 04 2005
%E A053898 Four more terms from Mishima's webpage added by _Max Alekseyev_, Jan 28 2012