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 A033934 #24 Jul 05 2025 05:30:39
%S A033934 4,121,10201,1002001,100020001,10000200001,1000002000001,
%T A033934 100000020000001,10000000200000001,1000000002000000001,
%U A033934 100000000020000000001,10000000000200000000001,1000000000002000000000001,100000000000020000000000001,10000000000000200000000000001
%N A033934 a(n) = (10^n + 1)^2.
%C A033934 The members of this sequence are both perfect squares and palindromes. Therefore A002779 is an infinite sequence. - _Ant King_, Jun 26 2011
%H A033934 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (111,-1110,1000).
%F A033934 a(n) = A062397(n)^2 = A066138(n) + A011557(n).
%F A033934 From _Elmo R. Oliveira_, Jul 04 2025: (Start)
%F A033934 G.f.: (4 - 323*x + 1210*x^2)/((1-x)*(1-10*x)*(1-100*x)).
%F A033934 E.g.f.: exp(x)*(1 + 2*exp(9*x) + exp(99*x)).
%F A033934 a(n) = 111*a(n-1) - 1110*a(n-2) + 1000*a(n-3). (End)
%t A033934 (10^Range[0,20]+1)^2 (* or *) LinearRecurrence[{111,-1110,1000},{4,121,10201},20] (* _Harvey P. Dale_, Feb 16 2016 *)
%o A033934 (PARI) my(x='x+O('x^15)); Vec((1210*x^2-323*x+4)/(-1000*x^3+1110*x^2-111*x+1)) \\ _Elmo R. Oliveira_, Jul 04 2025
%Y A033934 Cf. A002779 (palindromic squares), A000290 (squares), A002113 (palindromes).
%Y A033934 Cf. A011557, A062397, A066138.
%K A033934 nonn,base,easy
%O A033934 0,1
%A A033934 _Jeff Burch_
%E A033934 Better description from _Henry Bottomley_, Dec 07 2001
%E A033934 More terms from _Harvey P. Dale_, Feb 16 2016