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A227328
Number of n X n 0,1 arrays indicating 2 X 2 subblocks of some larger (n+1) X (n+1) binary array having two adjacent 1's and two adjacent 0's, with rows and columns of the latter in lexicographically nondecreasing order.
0
2, 11, 153, 4917, 366606, 66730314, 31357593706
OFFSET
1,1
COMMENTS
Diagonal of A227333.
EXAMPLE
Some solutions for n=4
..0..0..0..0....0..0..1..0....0..1..1..1....0..0..1..0....0..1..1..0
..0..0..0..0....1..1..0..0....1..0..1..1....0..0..1..0....0..1..1..0
..1..0..1..0....0..1..0..0....0..0..1..1....1..0..1..0....1..0..1..1
..0..1..0..0....0..0..0..0....0..1..0..0....1..0..0..1....0..0..1..0
CROSSREFS
Cf. A227333.
Sequence in context: A171184 A297676 A049462 * A287149 A188684 A143875
KEYWORD
nonn
AUTHOR
R. H. Hardin Jul 07 2013
STATUS
approved