0,7

The hexagonal lattice is the familiar 2-dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice.

I. Jensen, Table of n, a(n) for n = 0..69 (from link below)

I. Jensen, More terms

G. Nebe and N. J. A. Sloane, Home page for hexagonal (or triangular) lattice A2

Cf. A057374-A057405.

Sequence in context: A115859 A129170 A057389 this_sequence A007270 A057387 A109898

Adjacent sequences: A057379 A057380 A057381 this_sequence A057383 A057384 A057385

sign

N. J. A. Sloane (njas(AT)research.att.com), Aug 30 2000