A325408 Number of (2n+1) X (2n+1) black-and-white mirror-symmetric grids that are legal for crossword puzzles.

1, 5, 35, 436, 11348, 650798, 78816939, 19500572516, 10050221059942, 10777659213636406, 24081651896803403442

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: A059865 A376322 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