0,2

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).

J. W. Essam, Percolation and cluster size, in C. Domb and M. S. Green, Phase Transitions and Critical Phenomena, Ac. Press 1972, Vol. 2; see especially pp. 225-226.

M. F. Sykes and J. W. Essam, Critical percolation probabilities by series methods, Phys. Rev., 133 (1964), A310-A315.

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

Sequence in context: A085437 A024166 A103501 this_sequence A096045 A115712 A003765

Adjacent sequences: A003194 A003195 A003196 this_sequence A003198 A003199 A003200

nonn

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