Number of (2n+1) X (2n+1) black-and-white mirror-symmetric grids that are legal for crossword puzzles and have no all-black edges.

A325409

Number of (2n+1) X (2n+1) black-and-white mirror-symmetric grids that are legal for crossword puzzles and have no all-black edges.

Terms

    a(0) =1a(1) =2a(2) =20a(3) =269a(4) =8116a(5) =519400a(6) =67566361a(7) =17518353991

External references