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 A273234 #14 Sep 22 2020 10:23:01
%S A273234 9,889249,896809,908209,902942754289,924745719769,946618081249,
%T A273234 987107822089,910909843526089,9810767198166489,888909576913320169,
%U A273234 889214944824055249,889286612895723249,889972999762742809,890923059538260849,896642235371330809,896979367708462809
%N A273234 Squares that remain squares if you decrease them by 8 times a repunit with the same number of digits.
%C A273234 Any number ends in 9.
%H A273234 Giovanni Resta, <a href="/A273234/b273234.txt">Table of n, a(n) for n = 1..10000</a>
%e A273234 9 - 8*1 = 1 = 1^2;
%e A273234 889249 - 8*111111 = 361 = 19^2;
%e A273234 896809 - 8*111111 = 7921 = 89^2.
%p A273234 P:=proc(q,h) local n; for n from 1 to q do
%p A273234 if type(sqrt(n^2-h*(10^(ilog10(n^2)+1)-1)/9),integer) then print(n^2);
%p A273234 fi; od; end: P(10^9,8);
%t A273234 sol[k_] := Block[{x, e = IntegerLength@k, d = Divisors@ k}, Union[ #+k/# & /@ Select[ Take[d, Ceiling[ Length@d/2]], EvenQ[x = #+k/#] && IntegerLength[ x^2/4] == e &]]^2/4]; r[n_] := 8 (10^n-1)/9; Flatten[sol /@ r /@ Range[12]] (* _Giovanni Resta_, May 18 2016 *)
%Y A273234 Cf. A002275, A061844, A273299-A273233.
%K A273234 nonn,easy,base
%O A273234 1,1
%A A273234 _Paolo P. Lava_, May 18 2016
%E A273234 a(11)-a(17) from _Giovanni Resta_, May 18 2016