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A006742 Series for second perpendicular moment of hexagonal lattice.
(Formerly M2020)
1
2, 12, 46, 144, 402, 1040, 2548, 5992, 13632, 30220, 65486, 139404, 291770, 602908, 1229242, 2482792, 4959014, 9836840, 19323246, 37773464, 73182570, 141345292, 270647584, 517513972, 980893354 (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

I. Jensen, Table of n, a(n) for n = 1..82

I. G. Enting, A, J. Guttmann and I. Jensen, Low-Temperature Series Expansions for the Spin-1 Ising Model, J. Phys. A. 27 (21) (1994) 6987-7006. [arxiv:hep-lat/9410005

J. W. Essam, A. J. Guttmann and K. De'Bell, On two-dimensional directed percolation, J. Phys. A 21 (19) (1988), 3815-3832.

I. Jensen, More terms

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.

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

CROSSREFS

Sequence in context: A046991 A188982 A061990 * A003993 A129018 A302447

Adjacent sequences:  A006739 A006740 A006741 * A006743 A006744 A006745

KEYWORD

sign

AUTHOR

N. J. A. Sloane, Simon Plouffe

STATUS

approved

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Last modified January 17 16:44 EST 2019. Contains 319235 sequences. (Running on oeis4.)