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A006736 Series for first parallel moment of hexagonal lattice.
(Formerly M3597)
4
0, 4, 24, 104, 384, 1284, 4012, 11924, 34100, 94584, 255852, 677850, 1764482, 4523924, 11447870, 28636218, 70907326, 173991368, 423469988, 1023162920, 2455645268, 5858183260, 13898041838, 32804047708, 77067740230 (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..90 (from link below)

I. Jensen, More terms

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

CROSSREFS

Cf. A006803, A006809, A006737.

Sequence in context: A260217 A048806 A043009 * A165752 A166036 A120908

Adjacent sequences:  A006733 A006734 A006735 * A006737 A006738 A006739

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Simon Plouffe

STATUS

approved

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Last modified January 18 10:53 EST 2019. Contains 319271 sequences. (Running on oeis4.)