1,1

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).

J. Blease, Series expansions for the directed-bond percolation problem, J. Phys. C 10 (1977), 917-924.

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

Sequence in context: A014286 A000714 A090984 this_sequence A056823 A105544 A119917

Adjacent sequences: A006810 A006811 A006812 this_sequence A006814 A006815 A006816

nonn

N. J. A. Sloane (njas(AT)research.att.com).