0,2

The convex hull of a finite point set in dimension 2, say S, forms a convex polygon whose vertices are in S.

For any n >= 0, A000328(n) gives the number of elements of the set of points of norm <= n^2 in square lattice.

For symmetry reasons, a(n) is a multiple of 4 for any n > 0.

Table of n, a(n) for n=0..65.

Rémy Sigrist, C++ program for A292276

Rémy Sigrist, Illustration of the convex hulls for n=0..10

Wikipedia, Convex hull of a finite point set

See Links section.

(C++) See Links section.

Cf. A000328, A046109.

Sequence in context: A301705 A309456 A004024 * A278083 A086663 A003829

Adjacent sequences: A292273 A292274 A292275 * A292277 A292278 A292279

nonn

Rémy Sigrist, Sep 13 2017

approved