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 A036516 #12 Jul 27 2018 08:45:22
%S A036516 9,3969,29929,1999396,299739969,2909199969,19299599929,909995799969,
%T A036516 9499999990849,999999202999696,9969959993997969,90949999999997329,
%U A036516 9199999971969929929,199999969997999200969,19997911999199999979409,295191999919994299999969
%N A036516 Smallest square containing exactly n 9's.
%C A036516 a(20) > 10^28. - _Giovanni Resta_, Jul 27 2018
%H A036516 Giovanni Resta, <a href="/A036516/b036516.txt">Table of n, a(n) for n = 1..19</a>
%t A036516 a[n_] := Block[{k=1}, While[DigitCount[k^2, 10, 9] != n, k++]; k^2]; Array[a, 6] (* _Giovanni Resta_, Jul 27 2018 *)
%Y A036516 Cf. A048354. - _Jon E. Schoenfield_, Jan 24 2009
%K A036516 nonn,base
%O A036516 1,1
%A A036516 _David W. Wilson_
%E A036516 More terms from _Jon E. Schoenfield_, Jan 24 2009
%E A036516 a(16) from _Giovanni Resta_, Jul 27 2018