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A006803 Percolation series for hexagonal lattice.
(Formerly M2232)
5
1, 0, 0, -1, 0, -3, 1, -9, 6, -29, 27, -99, 112, -351, 450, -1275, 1782, -4704, 6998, -17531, 27324, -65758, 106211, -247669, 411291, -935107, 1587391, -3535398, 6108103, -13373929, 23438144, -50592067, 89703467, -191306745, 342473589 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,6

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

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..51

I. Jensen, More terms

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

CROSSREFS

Cf. A006809.

Sequence in context: A229759 A185580 A052931 * A197730 A231902 A143495

Adjacent sequences:  A006800 A006801 A006802 * A006804 A006805 A006806

KEYWORD

sign

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified January 20 14:40 EST 2019. Contains 319333 sequences. (Running on oeis4.)