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 A053887 #24 Oct 18 2024 14:36:43
%S A053887 1,81,121,8281,11881,128881,11282881,228281881,1112822881,
%T A053887 111128222881,11111282222881,222128888112121,228828882122281,
%U A053887 812121128112121,1111112822222881,8181222218111881,111111128222222881,11111111282222222881,1111111112822222222881,2118128181211211281281
%N A053887 Squares composed of digits {1,2,8}.
%C A053887 Includes all numbers of the form ((10^k-1)/3 + 26)^2 for k >= 3. - _Andrew Howroyd_, Sep 28 2024
%H A053887 Zhao Hui Du, <a href="/A053887/b053887.txt">Table of n, a(n) for n = 1..44</a>
%H A053887 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 A053887 a(n) = A053886(n)^2. - _Andrew Howroyd_, Oct 18 2024
%t A053887 Table[Select[FromDigits/@Tuples[{1,2,8},n],IntegerQ[Sqrt[#]]&],{n,18}]//Flatten (* _Harvey P. Dale_, Jun 03 2022 *)
%Y A053887 Cf. A053886.
%K A053887 nonn,base
%O A053887 1,2
%A A053887 _Patrick De Geest_, Mar 15 2000