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 A058474 #18 Jul 18 2025 08:31:00
%S A058474 1,9,1909190001999001011109190090109911991001,
%T A058474 10199000091990191001091091099001091999900190199000001
%N A058474 Squares composed of digits {0,1,9}, not ending with zero.
%H A058474 Patrick De Geest, <a href="https://www.worldofnumbers.com/threedigits.htm">Index to related sequences</a>.
%H A058474 Shyam Sunder Gupta, <a href="https://doi.org/10.1007/978-981-97-2465-9_2">Elegance of Squares, Cubes, and Higher Powers</a>, Exploring the Beauty of Fascinating Numbers, Springer (2025) Ch. 2, pp. 29-81.
%H A058474 Hisanori Mishima, <a href="https://www.asahi-net.or.jp/~KC2H-MSM/mathland/math02/math0210.htm#019">Sporadic tridigital solutions</a>.
%F A058474 a(n) = A058473(n)^2. - _Elmo R. Oliveira_, Jul 17 2025
%Y A058474 Cf. A058473.
%K A058474 nonn,base,more
%O A058474 1,2
%A A058474 _Patrick De Geest_, Nov 15 2000
%E A058474 a(4) from _Zhao Hui Du_, Feb 29 2024