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 A030484 #20 Jul 16 2025 13:41:22
%S A030484 25,225,256,625,5625,55225,225625,265225,266256,525625,26265625,
%T A030484 56625625,525555625,556252225,5252625625,255555525625,265652622225,
%U A030484 6255626265625,225255552522256,562222665225225,5222566262655625,22225226555625625,62566655262225625,65552556565552225
%N A030484 Squares composed of digits {2,5,6}.
%C A030484 Each term is either 25 or 56 mod 100 (which is used in the Mathematica program below to improve the search speed). - _Harvey P. Dale_, Jul 02 2016
%H A030484 Zhao Hui Du, <a href="/A030484/b030484.txt">Table of n, a(n) for n = 1..44</a>
%H A030484 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 A030484 Hisanori Mishima, <a href="https://www.asahi-net.or.jp/~KC2H-MSM/mathland/math02/math0210.htm#256">Sporadic tridigital solutions</a>.
%F A030484 a(n) = A030486(n)^2. - _Elmo R. Oliveira_, Jul 16 2025
%t A030484 Select[Flatten[Table[{FromDigits/@(Join[#,{2,5}]&/@Tuples[{2,5,6},n]), FromDigits/@ (Join[#,{5,6}]&/@Tuples[{2,5,6},n])},{n,0,14}]], IntegerQ[ Sqrt[#]]&]//Sort (* _Harvey P. Dale_, Jul 02 2016 *)
%Y A030484 Cf. A030486.
%K A030484 nonn,base
%O A030484 1,1
%A A030484 _Patrick De Geest_
%E A030484 Extended and corrected by _Patrick De Geest_, May 08 2000