A268020 The number of spheres on which the points defined by A222268 lie.

3, 29, 299, 2177, 10482, 41348

Offset

2,1

Comments

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 centred at the center of the cubic grid. a(n) is the total number of such spheres, including the radius-zero sphere.

Links

Table of n, a(n) for n=2..7.

Example

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.

Crossrefs

Cf. A222267, A222268.

Sequence in context: A340990 A112711 A155651 * A278934 A001947 A323569

Adjacent sequences: A268017 A268018 A268019 * A268021 A268022 A268023

Keyword

nonn,more

Author

Clive Tooth, Feb 28 2016

Status

approved