1,2

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

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

G. Szekeres and A. J. Guttmann, Spiral self-avoiding walks on the triangular lattice, J. Phys. A 20 (1987), 481-493.

Table of n, a(n) for n=1..30.

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

Sequence in context: A298880 A208483 A284735 * A036609 A027557 A120545

Adjacent sequences: A006774 A006775 A006776 * A006778 A006779 A006780

nonn

N. J. A. Sloane.

approved