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A193221
Number of n X n symmetric 0..3 arrays with no element equal to the sum mod 4 of any two of its horizontal and vertical neighbors
0
4, 27, 201, 2791, 77245, 4482957, 547681823, 138848752487, 71804214564925, 74948295541392333, 157072100264370812423, 659458569446754937883175, 5541778577891773501263989795, 93184605443427688066128310380963
OFFSET
1,1
EXAMPLE
Some solutions for 4X4
..1..1..3..3....1..1..1..3....3..3..1..3....1..3..3..3....3..3..1..3
..1..3..1..1....1..3..1..3....3..3..3..1....3..3..1..3....3..1..3..1
..3..1..1..1....1..1..1..1....1..3..3..1....3..1..3..1....1..3..1..3
..3..1..1..1....3..3..1..3....3..1..1..3....3..3..1..1....3..1..3..3
CROSSREFS
Sequence in context: A164311 A091125 A331796 * A091121 A026005 A059391
KEYWORD
nonn
AUTHOR
R. H. Hardin Jul 18 2011
STATUS
approved