

A006809


Bond percolation series for hexagonal lattice.
(Formerly M2796 M2797)


5



1, 3, 9, 25, 66, 168, 417, 1014, 2427, 5737, 13412, 31088, 71506, 163378, 371272, 839248, 1889019, 4235082, 9459687, 21067566, 46769977, 103574916, 228808544, 504286803, 1109344029, 2435398781, 5337497418, 11678931098
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OFFSET

0,2


COMMENTS

The hexagonal lattice is the familiar 2dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice.
The first negative term occurs at index 89.


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. Blease, Series expansions for the directedbond percolation problem, J. Phys. C 10 (1977), 917924.
J. W. Essam, A. J. Guttmann and K. De'Bell, On twodimensional directed percolation, J. Phys. A 21 (1988), 38153832.
I. Jensen, More terms
Iwan Jensen, Anthony J. Guttmann, Series expansions of the percolation probability for directed square and honeycomb lattices, J. Phys. A 28 (1995), no. 17, 48134833.
G. Nebe and N. J. A. Sloane, Home page for hexagonal (or triangular) lattice A2


CROSSREFS

Cf. A006803, A006736.
Sequence in context: A335472 A096322 A058396 * A081663 A245748 A181383
Adjacent sequences: A006806 A006807 A006808 * A006810 A006811 A006812


KEYWORD

sign


AUTHOR

N. J. A. Sloane, Simon Plouffe


STATUS

approved



