A132445 Number of n X n crossword puzzles with rotational symmetry and at most one black square per row.

1, 3, 5, 7, 16, 47, 135, 643

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) = 5 because the only acceptable 5 X 5 crossword puzzles are (using 1's for black squares and 0's for white) are:
00000 10000 10000 00001 00001
00000 00000 10000 00000 00001
00000 00000 00000 00000 00000
00000 00000 00001 00000 10000
00000 00001 00001 10000 10000

Crossrefs

Cf. A130578, A132443, A132444, A132446.

Sequence in context: A291736 A010070 A291107 * A307437 A070846 A078683

Adjacent sequences: A132442 A132443 A132444 * A132446 A132447 A132448

Keyword

nonn

Author

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

Status

approved