3,2

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.

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

Marc Brodie, Mathematica program

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

Cf. A130578, A132443, A132444, A132446.

Sequence in context: A291736 A010070 A291107 * A307437 A070846 A078683

Adjacent sequences: A132442 A132443 A132444 * A132446 A132447 A132448

nonn

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

approved