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 A036508 #14 Jul 14 2019 17:51:14
%S A036508 1,121,11881,1110916,11431161,111112681,11112111396,171511111321,
%T A036508 1113111511681,105111111121641,6111111111571216,111611104111115361,
%U A036508 1411111111712116441,1113101111111117041,1111116080161111121161,11111119101145491111121,516116117111111111421121
%N A036508 Smallest square containing exactly n 1's.
%C A036508 a(17) > 4*10^23. - _Jon E. Schoenfield_, Jan 04 2009
%C A036508 a(20) > 10^28. - _Giovanni Resta_, Jul 27 2018
%H A036508 Giovanni Resta, <a href="/A036508/b036508.txt">Table of n, a(n) for n = 1..19</a>
%t A036508 a[n_] := Block[{k=1}, While[DigitCount[k^2, 10, 1] != n, k++]; k^2]; Array[a, 7] (* _Giovanni Resta_, Jul 27 2018 *)
%Y A036508 Cf. A048346.
%K A036508 nonn,base
%O A036508 1,2
%A A036508 _David W. Wilson_
%E A036508 a(13)-a(16) from _Jon E. Schoenfield_, Jan 05 2009
%E A036508 a(17) from _Giovanni Resta_, Jul 27 2018