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A006737
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Series for second parallel moment of hexagonal lattice.
(Formerly M4275)
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3
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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; internal format)
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OFFSET
| 0,2
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COMMENTS
| The hexagonal lattice is the familiar 2-dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice.
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REFERENCES
| 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).
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LINKS
| 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
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CROSSREFS
| Cf. A006803, A006809, A006736, A006738.
Sequence in context: A152390 A200059 A183470 * A128869 A186669 A140606
Adjacent sequences: A006734 A006735 A006736 * A006738 A006739 A006740
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe (simon.plouffe(AT)gmail.com)
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