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 A111648 #28 Feb 06 2024 10:17:35
%S A111648 3,83,2811,95483,3243603,110187011,3743114763,127155714923,
%T A111648 4319551192611,146737584833843,4984758333158043,169335045742539611,
%U A111648 5752406796913188723,195412496049305876963
%N A111648 a(n) = A001541(n)^2 + A001653(n+1)^2 + A002315(n)^2.
%H A111648 Ray Chandler, <a href="/A111648/b111648.txt">Table of n, a(n) for n = 0..652</a>
%H A111648 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (35,-35,1).
%F A111648 a(n) = A038761(n)^2 + 2, e.g., 95483 = 309^2 + 2.
%F A111648 a(n) = A001652(2*n+1) - A001109(n+1)^2 - Sum_{k=1..n-1} A038723(2*n), e.g., 95483 = 137903 - 204^2 - (23 + 781).
%F A111648 For n > 0, 2*a(n) + A001652(2*n-1) = A001653(2*n+2), e.g., 2*2811 + 119 = 5741.
%F A111648 G.f.: -(11*x^2-22*x+3) / ((x-1)*(x^2-34*x+1)). - _Colin Barker_, Dec 14 2014 (Empirical g.f. confirmed for more terms and recurrence of source sequences. - _Ray Chandler_, Feb 05 2024)
%e A111648 a(1) = 83 = 3^2+5^2+7^2.
%t A111648 LinearRecurrence[{35, -35, 1}, {3, 83, 2811}, 20] (* _Paolo Xausa_, Feb 06 2024 *)
%Y A111648 Cf. A001541, A001653, A002315, A111647, A111649.
%K A111648 nonn,easy
%O A111648 0,1
%A A111648 _Charlie Marion_, Aug 24 2005