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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
0
1, 3, 36, 813, 44379, 6022992, 2110707595, 1972236759492
OFFSET
1,2
COMMENTS
Diagonal of A227256
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: A186730 A224347 A377548 * A326273 A224006 A004824
KEYWORD
nonn
AUTHOR
R. H. Hardin Jul 04 2013
STATUS
approved