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 A058444 #16 Oct 18 2024 14:36:05
%S A058444 4,9,49,9409,44944,994009,9909904,99940009,404090404,9999400009,
%T A058444 999994000009,4004009004004,9449494444009,99999940000009,
%U A058444 9999999400000009,40004000900040004,999999994000000009,99999999940000000009,400004000090000400004,9999999999400000000009
%N A058444 Squares composed of digits {0,4,9}, not ending with zero.
%C A058444 Includes all numbers of the form (10^k - 3)^2 for k >= 1 and of the form (2*100^k + 10^k + 2)^2 for k >= 1. - _Andrew Howroyd_, Oct 18 2024
%H A058444 Zhao Hui Du, <a href="/A058444/b058444.txt">Table of n, a(n) for n = 1..54</a>
%H A058444 Patrick De Geest, <a href="http://www.worldofnumbers.com/threedigits.htm">Index to related sequences</a>
%H A058444 Hisanori Mishima, <a href="http://www.asahi-net.or.jp/~KC2H-MSM/mathland/math02/math0210.htm#049">Sporadic tridigital solutions</a>
%F A058444 a(n) = A058443(n)^2. - _Andrew Howroyd_, Oct 18 2024
%Y A058444 Cf. A058443.
%K A058444 nonn,base
%O A058444 1,1
%A A058444 _Patrick De Geest_, Nov 15 2000