A132446 The number of n x n crossword puzzles with at most one black square per row up to horizontal/vertical symmetry.

1, 2, 3, 4, 10, 24, 71, 322

Offset

3,2

Comments

Acceptable crossword puzzles must have all words of length 3 or more, at least one word in each row and each column and be connected.

Links

Table of n, a(n) for n=3..10.

Marc Brodie, Mathematica program

Example

a(5) = 3 because up to symmetry the only 5 x 5 acceptable crossword puzzles with at most one black square per row (using 1's for black squares and 0's for white) are:
00000 10000 10000
00000 00000 10000
00000 00000 00000
00000 00000 00001
00000 00001 00001

Crossrefs

Cf. A130578, A132443, A132444, A132445.

Sequence in context: A132135 A372933 A131871 * A332838 A123700 A005433

Adjacent sequences: A132443 A132444 A132445 * A132447 A132448 A132449

Keyword

nonn

Author

Marc Brodie (mbrodie(AT)wju.edu), Aug 21 2007, Aug 22 2007

Status

approved