A227251 Number of n X n binary arrays indicating whether each 2X2 subblock of a larger binary array has lexicographically nondecreasing rows and columns, for some larger (n+1)X(n+1) binary array with rows and columns of the latter in lexicographically nondecreasing order

1, 3, 36, 813, 44379, 6022992, 2110707595, 1972236759492

Offset

1,2

Comments

Diagonal of A227256

Links

Table of n, a(n) for n=1..8.

Example

Some solutions for n=4
..1..0..1..1....1..1..0..0....1..1..1..1....1..1..1..0....1..1..1..1
..0..1..1..1....1..0..1..1....1..1..0..0....1..1..0..0....1..1..0..1
..0..1..1..1....1..0..1..1....1..0..0..1....1..0..1..1....1..0..1..0
..1..1..1..1....1..1..1..0....0..0..1..0....0..1..1..1....1..1..0..1

Crossrefs

Sequence in context: A122220 A186730 A224347 * A326273 A224006 A004824

Adjacent sequences: A227248 A227249 A227250 * A227252 A227253 A227254

Keyword

nonn

Author

R. H. Hardin Jul 04 2013

Status

approved