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 A268020 #21 Apr 28 2025 15:50:07 %S A268020 3,29,299,2177,10482,41348 %N A268020 The number of spheres on which the points defined by A222268 lie. %C A268020 Given a cubic n X n X n grid of points, a collection of lines is produced by constructing a line through every pair of points. A222267 gives the count of such lines. A collection of points is produced by taking the points of intersection of those lines. A222268 gives the count of such points. Each point in such a collection will lie on a particular sphere centered at the center of the cubic grid. a(n) is the total number of such spheres, including the radius-zero sphere. %e A268020 A 2 X 2 X 2 grid of points defines 28 distinct lines which intersect in a total of 15 points (including the original 8 points). One of these points is the center of the grid, 8 of them are the vertices of the cube and 6 are the face-centers of the cube. So, a(2) = 3. %Y A268020 Cf. A222267, A222268. %K A268020 nonn,more %O A268020 2,1 %A A268020 _Clive Tooth_, Feb 28 2016