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 A053414 #14 Jun 06 2018 16:16:21
%S A053414 0,2,2,8,12,22,26,40,48,62,78,96,108,134,154,180,196,230,250,280,312,
%T A053414 346,378,412,452,494,526,576,612,658,698,756,800,850,906,964,1012,
%U A053414 1074,1130,1196,1252,1322,1378,1448,1516,1594,1654,1732,1808,1882,1954
%N A053414 Circle numbers (version 2): a(n) is the number of points (i,j), i,j integers, contained in a circle of diameter n, centered at (0, 1/2).
%C A053414 Lim_{n->infinity} a(n)/n^2 = Pi/4.
%H A053414 G. C. Greubel, <a href="/A053414/b053414.txt">Table of n, a(n) for n = 0..1000</a>
%t A053414 a[n_] := (m = Ceiling[n/2]; Sum[ Boole[ n > 2*i && 2*i+n > 0 && n^2 - 4*i^2 + 4*j - 4*j^2 - 1 >= 0 ], {i, -m, m}, {j, -Ceiling @ Sqrt[ m^2-i^2 ], Ceiling @ Sqrt[ m^2-i^2 ]}]); Table[a[n], {n, 0, 50}] (* _Jean-François Alcover_, Jun 06 2013 *)
%Y A053414 Cf. A053411, A053415, A053416, A053417.
%K A053414 easy,nonn
%O A053414 0,2
%A A053414 Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Jan 10 2000