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 A180737 #16 Oct 05 2019 09:16:26
%S A180737 9,81,961,9025,96721,990025,9966649,99980001,999761161,9999400009,
%T A180737 99998250625,999946000729,9999989500176,99999960000004,
%U A180737 999999455981824,9999998600000049,99999998724439696,999999998000000001
%N A180737 a(n) is the largest n-digit square whose sum of digits is also a square.
%H A180737 Daniel Mondot, <a href="/A180737/b180737.txt">Table of n, a(n) for n = 1..258</a>
%t A180737 lnds[n_]:=Module[{s=Floor[Sqrt[10^n-1]]},While[!IntegerQ[Sqrt[Total[ IntegerDigits[ s^2]]]],s--];s^2]; Array[lnds,20] (* _Harvey P. Dale_, Mar 28 2013 *)
%Y A180737 Cf. A007953, A053057, A180738.
%K A180737 nonn,base,easy
%O A180737 1,1
%A A180737 _Daniel Mondot_, Oct 08 2010