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 A343098 #18 Jun 21 2021 06:05:27
%S A343098 1,4,6,11,14,22,27,40,49,71,87,124,151,211,254,347,412,550,644,841,
%T A343098 972,1244,1421,1786,2019,2497,2797,3410,3789,4561,5032,5989,6566,7736,
%U A343098 8434,9847,10682,12370,13359,15356,16517,18859,20211,22936,24499,27647,29442,33055
%N A343098 Number of palindromes < 10^n whose squares are also palindromes.
%C A343098 Partial sum of A218035. Number of terms in A057135 < 10^n.
%H A343098 Chai Wah Wu, <a href="/A343098/b343098.txt">Table of n, a(n) for n = 0..10000</a>
%H A343098 <a href="/index/Rec#order_09">Index entries for linear recurrences with constant coefficients</a>, signature (1,4,-4,-6,6,4,-4,-1,1).
%F A343098 a(n) = #{i:A057135(i)<10^n}.
%F A343098 For n > 0, a(n) = Sum_{i=1..n} A218035(i).
%F A343098 a(n) = a(n-1) + 4*a(n-2) - 4*a(n-3) - 6*a(n-4) + 6*a(n-5) + 4*a(n-6) - 4*a(n-7) - a(n-8) + a(n-9) for n > 9.
%F A343098 G.f.: (-x^9 + x^7 - x^6 - 6*x^5 - x^4 + 7*x^3 + 2*x^2 - 3*x - 1)/((x - 1)^5*(x + 1)^4).
%F A343098 a(n) = 1491 + 904*n + 510*n^2 - 52*n^3 + 6*n^4 + (-1)^n * (45 - 296*n + 42*n^2 - 4*n^3) for n>0. - _Greg Dresden_, Jun 20 2021
%e A343098 a(2) = 6 since the only palindromes < 100 whose square are palindromes are 0,1,2,3,11,22.
%o A343098 (Python)
%o A343098 A343098_list = [1, 4, 6, 11, 14, 22, 27, 40, 49, 71]
%o A343098 for i in range(10**3): A343098_list.append(A343098_list[-1] + 4*A343098_list[-2] - 4*A343098_list[-3] - 6*A343098_list[-4] + 6*A343098_list[-5] + 4*A343098_list[-6] - 4*A343098_list[-7] - A343098_list[-8] + A343098_list[-9])
%Y A343098 Cf. A000290, A002113, A002779, A057136, A057135, A218035.
%K A343098 nonn,base
%O A343098 0,2
%A A343098 _Chai Wah Wu_, Apr 04 2021