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A007239
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Energy function for hexagonal lattice.
(Formerly M2562)
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0
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3, 6, 12, 24, 54, 138, 378, 1080, 3186, 9642, 29784, 93552, 297966, 960294, 3126408, 10268688, 33989388, 113277582, 379833906, 1280618784
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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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
| C. Domb, Ising model, in Phase Transitions and Critical Phenomena, vol. 3, ed. C. Domb and M. S. Green, Academic Press, 1974; p. 386.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
| G. Nebe and N. J. A. Sloane, Home page for hexagonal (or triangular) lattice A2
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CROSSREFS
| Sequence in context: A165929 A084717 A102254 * A088970 A068425 A136444
Adjacent sequences: A007236 A007237 A007238 * A007240 A007241 A007242
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KEYWORD
| nonn
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AUTHOR
| Simon Plouffe (simon.plouffe(AT)gmail.com)
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