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A006740 Series for first parallel moment of hexagonal lattice.
(Formerly M3563)
1
0, 4, 20, 68, 196, 512, 1256, 2936, 6628, 14528, 31140, 65414, 135276, 275656, 555216, 1105726, 2182380, 4268906, 8290740, 15984420, 30638312, 58369924, 110665328, 208734268, 392103508, 733311754, 1366650536, 2537201920 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

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

REFERENCES

J. W. Essam, A. J. Guttmann and K. De'Bell, On two-dimensional directed percolation, J. Phys. A 21 (1988), 3815-3832.

Jensen, Iwan; Guttmann, Anthony J.; Series expansions of the percolation probability for directed square and honeycomb lattices. J. Phys. A 28 (1995), no. 17, 4813-4833.

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

LINKS

I. Jensen, Table of n, a(n) for n = 0..82 (from link below)

I. G. Enting, A, J. Guttmann and I. Jensen, Low-Temperature Series Expansions for the Spin-1 Ising Model, J. Phys. A. 27 (1994) 6987-7006.

I. Jensen, More terms

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

CROSSREFS

Sequence in context: A319779 A287244 A123613 * A291526 A303011 A197426

Adjacent sequences:  A006737 A006738 A006739 * A006741 A006742 A006743

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Simon Plouffe

STATUS

approved

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Last modified January 18 16:40 EST 2019. Contains 319271 sequences. (Running on oeis4.)