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 A031152 #20 Oct 18 2024 16:29:43
%S A031152 4,25,225,4225,55225,442225,4545424,5452225,42445225,44422225,
%T A031152 544522225,2224254244,4424245225,4444222225,4554225225,54445222225,
%U A031152 55255554225,444242245225,444442222225,5444452222225,44442422245225,44444422222225,544444522222225
%N A031152 Squares composed of digits {2,4,5}.
%C A031152 Includes all numbers of the form (2*(10^k-1)/3 - 1)^2 for k >= 1, of the form (2*(10^k - 1)/3 - 151)^2 for k >= 4, and of the form (7*(10^k-1)/3 + 4)^2 for k >= 2. - _Andrew Howroyd_, Oct 18 2024
%H A031152 Zhao Hui Du, <a href="/A031152/b031152.txt">Table of n, a(n) for n = 1..106</a>
%H A031152 Patrick De Geest, <a href="http://www.worldofnumbers.com/threedigits.htm">Squares containing at most three distinct digits, Index entries for related sequences</a>
%F A031152 a(n) = A031154(n)^2. - _Andrew Howroyd_, Oct 18 2024
%t A031152 Flatten[Table[Select[FromDigits/@Tuples[{2,4,5},n],IntegerQ[Sqrt[#]]&],{n,14}]] (* _Harvey P. Dale_, Oct 07 2013 *)
%Y A031152 Cf. A031154.
%K A031152 nonn,base
%O A031152 1,1
%A A031152 _Patrick De Geest_
%E A031152 Extended and corrected by author 03/2000.
%E A031152 a(22)-a(23) from _Alois P. Heinz_, Apr 01 2015