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A280803
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Number of n X n 0..1 arrays with no element equal to more than two of its horizontal, vertical and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.
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0
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0, 1, 56, 2146, 41931, 547197, 5219491, 39260363, 247768745, 1379016025, 7040775017
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OFFSET
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1,3
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COMMENTS
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LINKS
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EXAMPLE
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Some solutions for n=4
..0..1..0..1. .0..0..1..0. .0..0..1..0. .0..1..1..0. .0..1..0..1
..0..1..1..1. .0..1..1..1. .1..1..0..1. .1..0..0..0. .0..0..0..1
..0..1..0..0. .0..0..0..1. .0..0..1..0. .0..1..0..1. .1..1..1..0
..0..0..1..1. .1..1..0..1. .1..1..1..0. .0..1..1..0. .0..0..0..0
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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