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A200749
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Number of meanders filling out an n X n grid, not reduced for symmetry.
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3
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1, 1, 0, 11, 320, 71648, 55717584, 213773992667, 3437213982024260, 249555807519163873078, 78627163663841340597702692, 109477494899001088619906813170744, 666376868834051436218404625691790011056, 17813932068751803215543399261217225231408150272, 2084618062581510894785237376608868017658716989948775752, 1069049587048126292657245511018395164729584995637677006604201633, 2399885835948485973061191866831331382214612321025714609065977840609754872
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OFFSET
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1,4
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COMMENTS
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The sequence counts the closed paths that visit every cell of an n X n square lattice at least once, that never cross any edge between adjacent squares more than once, and that do not self-intersect. Paths related by rotation and/or reflection of the square lattice are counted separately.
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LINKS
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EXAMPLE
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a(1) counts the paths that visit the single cell of the 1 X 1 lattice: there is one, the "fat dot".
The 11 solutions for n=4 are illustrated in the supporting .png file.
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CROSSREFS
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A200000 gives the reduced version of the sequence (rotations/reflections not considered distinct).
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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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