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A227120 Number of n X n 0,1 arrays indicating 2X2 subblocks of some larger (n+1)X(n+1) binary array having a sum of zero, with rows and columns of the latter in lexicographically nondecreasing order 0
2, 7, 33, 295, 5820, 241783, 21458929, 4109192774, 1709864974106 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Diagonal of A227125

LINKS

Table of n, a(n) for n=1..9.

EXAMPLE

Some solutions for n=4

..0..0..0..0....1..0..0..0....0..0..0..0....1..1..1..1....0..0..0..0

..0..0..1..1....0..0..0..0....0..1..1..1....1..1..1..1....0..0..1..1

..0..1..1..1....0..0..1..1....0..1..1..1....1..1..1..1....0..0..1..1

..0..0..1..0....0..0..1..1....0..1..1..0....0..0..0..0....0..1..0..0

CROSSREFS

Sequence in context: A143889 A241767 A222940 * A023053 A058915 A273030

Adjacent sequences:  A227117 A227118 A227119 * A227121 A227122 A227123

KEYWORD

nonn

AUTHOR

R. H. Hardin Jul 01 2013

STATUS

approved

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Last modified June 26 00:10 EDT 2019. Contains 324367 sequences. (Running on oeis4.)