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A325408
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Number of (2n+1) X (2n+1) black-and-white mirror-symmetric grids that are legal for crossword puzzles.
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3
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1, 5, 35, 436, 11348, 650798, 78816939, 19500572516, 10050221059942, 10777659213636406, 24081651896803403442
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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COMMENTS
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Rules: Every white square must be "checked" (in both a horizontal and vertical word), words must be at least 3 letters long, the whole grid must be symmetric under both left-right and top-bottom mirror symmetry, and the set of white squares must be connected.
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LINKS
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Table of n, a(n) for n=1..11.
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CROSSREFS
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Cf. A323838, A323839, A325409.
There are many other OEIS sequences related to crossword puzzles: search for "crossword puzzle" (without the quotes).
Sequence in context: A204290 A059865 A247596 * A097492 A125802 A034217
Adjacent sequences: A325405 A325406 A325407 * A325409 A325410 A325411
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KEYWORD
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nonn,more
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AUTHOR
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Michael Kleber, Apr 23 2019
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EXTENSIONS
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a(11) added by Akshay Ravikumar, Jun 20 2019
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STATUS
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approved
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