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 A055427 #26 Aug 03 2025 08:42:59
%S A055427 1,7,29,123,425,1343,4197,12435,33809,84663,198765,444907,959801,
%T A055427 2005615,4064821,7988867,15221537,28122727,50423741,87851099,
%U A055427 148962249,246243487,397527813,627798387,971451697,1475103511,2201030157
%N A055427 Number of points in Z^n of norm <= 3.
%H A055427 Andrew Howroyd, <a href="/A055427/b055427.txt">Table of n, a(n) for n = 0..1000</a>
%H A055427 <a href="/index/Rec#order_10">Index entries for linear recurrences with constant coefficients</a>, signature (10, -45, 120, -210, 252, -210, 120, -45, 10, -1).
%F A055427 Appears to satisfy a 9-degree polynomial. - _Ralf Stephan_, Mar 07 2004
%F A055427 Empirical g.f.: (x+1)*(93*x^8+620*x^7-848*x^6+516*x^5-150*x^4+20*x^3+8*x^2-4*x+1) / (x-1)^10. - _Colin Barker_, Jul 07 2013
%F A055427 Above conjectures 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
%F A055427 a(n) = 1 +1126/315*n +84668/2835*n^3 -418/45*n^2 +2152/135*n^5 -64/15*n^6 +584/945*n^7 -2/45*n^8 -152/5*n^4 +4/2835*n^9. - _R. J. Mathar_, Aug 03 2025
%t A055427 a[n_] := SeriesCoefficient[1/(1-x) Sum[x^(i^2), {i, -3, 3}]^n, {x, 0, 9}];
%t A055427 a /@ Range[0, 26] (* _Jean-François Alcover_, Sep 29 2019, from A302997 *)
%Y A055427 Row n=3 of A302997. Column 9 of A122510.
%K A055427 nonn
%O A055427 0,2
%A A055427 _David W. Wilson_