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 A119677 #28 Jul 19 2024 08:48:16
%S A119677 0,0,4,16,32,60,88,120,164,216,276,332,392,476,556,648,732,832,936,
%T A119677 1052,1176,1288,1428,1560,1696,1860,2016,2180,2340,2512,2700,2876,
%U A119677 3080,3276,3488,3712,3908,4144,4360,4620,4864,5096,5356,5616,5900
%N A119677 a(n) is the number of complete squares that fit inside the circle with radius n, drawn on squared paper at (0, 0).
%H A119677 David Dewan, <a href="/A119677/b119677.txt">Table of n, a(n) for n = 0..10000</a>
%H A119677 David Dewan, <a href="/A119677/a119677.pdf">Drawings for n=1..12</a>
%F A119677 a(n) = 4 * A001182(n).
%F A119677 Limit_{n->oo} a(n)/(n^2) = Pi.
%t A119677 a[n_] := 4 Sum[Floor[Sqrt[n^2 - k^2]], {k, n - 1}];
%t A119677 Array[a, 45, 0] (* _David Dewan_, May 27 2024 *)
%o A119677 (Python)
%o A119677 from math import isqrt
%o A119677 def A119677(n): return sum(isqrt(k*((n<<1)-k)) for k in range(1,n))<<2 # _Chai Wah Wu_, Jul 18 2024
%Y A119677 Cf. A001182.
%K A119677 nonn
%O A119677 0,3
%A A119677 Tomas Kyselica (Tomas.Kyselica(AT)gmail.com), Jul 29 2006
%E A119677 More terms from _Don Reble_, Aug 01 2006
%E A119677 Name clarified by _Kirill Zolotuskiy_, Apr 15 2023