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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

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)

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

I. Jensen, More terms

Iwan Jensen, Anthony J. Guttmann, Series expansions of the percolation probability for directed square and honeycomb lattices, arXiv:cond-mat/9509121, 1995; J. Phys. A 28 (1995), no. 17, 4813-4833.

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 June 2 12:24 EDT 2020. Contains 334771 sequences. (Running on oeis4.)