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A006737 Series for second parallel moment of hexagonal lattice.
(Formerly M4275)
0, 6, 68, 442, 2218, 9528, 36834, 131856, 445000, 1433294, 4444006, 13349510, 39041224, 111583236, 312618368, 860662498, 2333112020, 6238124024, 16474149036, 43023953304, 111230237224, 284926172100, 723731637254 (list; graph; refs; listen; history; text; internal format)



The hexagonal lattice is the familiar 2-dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice.


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).


I. Jensen, Table of n, a(n) for n = 0..90 (from link below)

I. G. Enting, A, J. Guttmann and I. Jensen, Low-Temperature Series Expansions for the Spin-1 Ising Model, J. Phys. A. 27 (1994) 6987-7006.

I. Jensen, More terms

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


Cf. A006803, A006809, A006736, A006738.

Sequence in context: A200059 A183470 A281051 * A128869 A186669 A258134

Adjacent sequences:  A006734 A006735 A006736 * A006738 A006739 A006740




N. J. A. Sloane, Simon Plouffe



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Last modified January 16 00:02 EST 2019. Contains 319184 sequences. (Running on oeis4.)