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A006813 Percolation series for directed hexagonal lattice.
(Formerly M2778)
0
3, 9, 21, 48, 105, 219, 459, 936 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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

Table of n, a(n) for n=1..8.

J. Blease, Series expansions for the directed-bond percolation problem, J. Phys C vol 10 no 7 (1977), 917-924.

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

CROSSREFS

Sequence in context: A273845 A090984 A319781 * A274230 A056823 A105544

Adjacent sequences:  A006810 A006811 A006812 * A006814 A006815 A006816

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified August 9 04:30 EDT 2020. Contains 336319 sequences. (Running on oeis4.)