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A006836 Percolation series for directed hexagonal lattice.
(Formerly M1379)
1
1, 0, 0, -1, -2, -5, -10, -20, -41, -86, -182, -393, -853, -1887, -4208, -9445, -21350, -48612, -111307, -255236, -590543, -1362919, -3182137, -7362611, -17377129, -40125851, -96106251, -219681825, -539266908, -1200140540 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

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..35 (from link below)

I. Jensen, More terms

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

CROSSREFS

Cf. A006739.

Sequence in context: A266462 A293319 A267589 * A129847 A176692 A212951

Adjacent sequences:  A006833 A006834 A006835 * A006837 A006838 A006839

KEYWORD

sign

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified January 23 01:45 EST 2019. Contains 319365 sequences. (Running on oeis4.)