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 A030487 #18 Mar 09 2024 20:14:07
%S A030487 5,15,85,165,235,1665,15085,16665,166665,268835,1666665,5076665,
%T A030487 16666665,52683515,165898335,166666665,278433515,507668915,850032485,
%U A030487 1508559835,1666666665,15085017485,16666666665,166666666665
%N A030487 When squared gives number composed of digits {2, 5, 7}.
%H A030487 Zhao Hui Du, <a href="/A030487/b030487.txt">Table of n, a(n) for n = 1..45</a>
%H A030487 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 A030487 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>)
%e A030487 5^2 = 25, so 5 is in the sequence.
%e A030487 15^2 = 225, so 15 is in the sequence.
%e A030487 25^2 = 625, which has a 2 and 5 but also a 6, so 25 is not in the sequence.
%t A030487 Select[5Range[1, 9999, 2], Complement[IntegerDigits[#^2], {2, 5, 7}] == {} &] (* _Alonso del Arte_, Feb 25 2020 *)
%Y A030487 Cf. A030485.
%K A030487 nonn,base
%O A030487 1,1
%A A030487 _Patrick De Geest_
%E A030487 Extended and corrected by author 03/2000.
%E A030487 More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 03 2005