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 A055428 #20 Jun 27 2024 10:44:10
%S A055428 1,9,49,257,1281,5913,23793,88273,306049,995241,3083569,9217057,
%T A055428 26631041,74164665,198807793,513829617,1284656385,3117323593,
%U A055428 7360510001,16939394369,38039783425,83427144281,178841051889
%N A055428 Number of points in Z^n of norm <= 4.
%H A055428 Andrew Howroyd, <a href="/A055428/b055428.txt">Table of n, a(n) for n = 0..1000</a>
%H A055428 <a href="/index/Rec#order_17">Index entries for linear recurrences with constant coefficients</a>, signature (17, -136, 680, -2380, 6188, -12376, 19448, -24310, 24310, -19448, 12376, -6188, 2380, -680, 136, -17, 1).
%F A055428 Empirical g.f.: -(1201*x^16 +46896*x^15 +180864*x^14 -238504*x^13 -86788*x^12 +380032*x^11 -353440*x^10 +186568*x^9 -65418*x^8 +17264*x^7 -3968*x^6 +1000*x^5 -164*x^4 -32*x^3 +32*x^2 -8*x +1) / (x -1)^17. - _Colin Barker_, Jul 07 2013
%F A055428 Above conjecture confirmed by later additions of b-file from Andrew Howroyd and program from _Jean-François Alcover_ with connection to A302997. - _Ray Chandler_, Jun 27 2024
%t A055428 a[n_] := SeriesCoefficient[1/(1-x) Sum[x^(i^2), {i, -4, 4}]^n, {x, 0, 16}];
%t A055428 a /@ Range[0, 22] (* _Jean-François Alcover_, Sep 29 2019, from A302997 *)
%Y A055428 Row n=4 of A302997.
%K A055428 nonn
%O A055428 0,2
%A A055428 _David W. Wilson_