

A006737


Series for second parallel moment of hexagonal lattice.
(Formerly M4275)


3



0, 6, 68, 442, 2218, 9528, 36834, 131856, 445000, 1433294, 4444006, 13349510, 39041224, 111583236, 312618368, 860662498, 2333112020, 6238124024, 16474149036, 43023953304, 111230237224, 284926172100, 723731637254
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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.


REFERENCES

J. W. Essam, A. J. Guttmann and K. De'Bell, On twodimensional directed percolation, J. Phys. A 21 (1988), 38153832.
Jensen, Iwan; Guttmann, Anthony J.; Series expansions of the percolation probability for directed square and honeycomb lattices. J. Phys. A 28 (1995), no. 17, 48134833.
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)
I. G. Enting, A, J. Guttmann and I. Jensen, LowTemperature Series Expansions for the Spin1 Ising Model, J. Phys. A. 27 (1994) 69877006.
I. Jensen, More terms
G. Nebe and N. J. A. Sloane, Home page for hexagonal (or triangular) lattice A2


CROSSREFS

Cf. A006803, A006809, A006736, A006738.
Sequence in context: A200059 A183470 A281051 * A128869 A186669 A258134
Adjacent sequences: A006734 A006735 A006736 * A006738 A006739 A006740


KEYWORD

nonn


AUTHOR

N. J. A. Sloane, Simon Plouffe


STATUS

approved



