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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 (list; graph; refs; listen; history; text; internal format)
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 * A224006 A004824 A132912

Adjacent sequences:  A227248 A227249 A227250 * A227252 A227253 A227254

KEYWORD

nonn

AUTHOR

R. H. Hardin Jul 04 2013

STATUS

approved

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Last modified August 22 03:22 EDT 2017. Contains 290942 sequences.