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A054759
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Number of Eulerian orientations of the n X n square lattice (with wrap-around), i.e., number of arrow configurations on n X n grid that satisfy the square ice rule.
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5
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4, 18, 148, 2970, 143224, 16448400, 4484823396, 2901094068042, 4448410550095612, 16178049740086515288, 139402641051212392498528, 2849295959501939989625992464, 137950545200232788276834783781648, 15844635835975276495290739119895808472
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OFFSET
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1,1
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COMMENTS
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The n X n square lattice with wrap around is also called the torus grid graph. - Andrew Howroyd, Jan 11 2018
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REFERENCES
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Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 412-416.
Computed by Jennifer Henry in Dec. 1998.
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LINKS
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FORMULA
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Elliot Lieb proved that lim_{n->oo} a(n)^(1/n^2) = (4/3)^(3/2). See A118273.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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