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 A036513 #14 Apr 26 2021 15:50:13
%S A036513 16,676,46656,1666681,26666896,4666665969,26661664656,616686666436,
%T A036513 12666666068676,696626660666596,16666569616666761,64666665664666569,
%U A036513 666566667666656964,16656666666663616576,6466267667066666666596,46366666666326666766276
%N A036513 Smallest square containing exactly n 6's.
%C A036513 a(21) > 10^28. - _Giovanni Resta_, Jul 27 2018
%H A036513 Giovanni Resta, <a href="/A036513/b036513.txt">Table of n, a(n) for n = 1..20</a>
%e A036513 a(n) = A048351(n)^2.
%t A036513 a[n_] := Block[{k=1}, While[DigitCount[k^2, 10, 6] != n, k++]; k^2]; Array[a, 6] (* _Giovanni Resta_, Jul 27 2018 *)
%Y A036513 Cf. A048351. - _Jon E. Schoenfield_, Jan 24 2009
%K A036513 nonn,base
%O A036513 1,1
%A A036513 _David W. Wilson_
%E A036513 a(13)-a(15) from _Jon E. Schoenfield_, Jan 14 2009
%E A036513 a(16) from _Giovanni Resta_, Jul 27 2018