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A325408 Number of (2n+1) X (2n+1) black-and-white mirror-symmetric grids that are legal for crossword puzzles. 3
1, 5, 35, 436, 11348, 650798, 78816939, 19500572516, 10050221059942, 10777659213636406, 24081651896803403442 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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.

LINKS

Table of n, a(n) for n=1..11.

CROSSREFS

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

KEYWORD

nonn,more

AUTHOR

Michael Kleber, Apr 23 2019

EXTENSIONS

a(11) added by Akshay Ravikumar, Jun 20 2019

STATUS

approved

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Last modified October 23 14:54 EDT 2019. Contains 328345 sequences. (Running on oeis4.)