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 A047809 #11 Mar 31 2012 20:30:55
%S A047809 1,2,5,9,15,23,32,43,55,70,86,103,122,143,166,190,215,243,273,304,336,
%T A047809 371,406,443,482,523,566,611,656,704,753,803,855,910,966,1024,1083,
%U A047809 1145,1207,1270,1336,1404,1474,1544,1616,1690,1766,1843,1922,2004
%N A047809 a(n) counts different values of i^2+j^2+k^2 <= n^2 or number of distances from the origin to all integer points inside a sphere of radius n.
%H A047809 T. D. Noe, <a href="/A047809/b047809.txt">Table of n, a(n) for n = 0..1000</a>
%F A047809 a(n) = number of b(i) <= n^2, b() = A000378.
%t A047809 Table[ Length@Union@Flatten@Table[ i^2+j^2+k^2, {i, 0, n}, {j, 0, Min[ i, Floor[ Sqrt[ n^2-i^2 ] ] ]}, {k, 0, Min[ j, Floor[ Sqrt[ n^2-i^2-j^2 ] ] ]} ], {n, 0, 64} ]
%Y A047809 Cf. A047808, A000378.
%K A047809 nonn,easy,nice
%O A047809 0,2
%A A047809 _Wouter Meeussen_,_David W. Wilson_