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A281694
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Number of 2Xn 0..2 arrays with no element equal to more than one of its horizontal, diagonal or antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.
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1
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0, 0, 6, 272, 2516, 19168, 120824, 692320, 3728304, 19162048, 95114144, 459530496, 2172420416, 10088686592, 46160383360, 208560904704, 932182234880, 4127576462336, 18126823531008, 79031039336448, 342350615184384
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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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FORMULA
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Empirical: a(n) = 12*a(n-1) -54*a(n-2) +136*a(n-3) -324*a(n-4) +720*a(n-5) -1064*a(n-6) +1632*a(n-7) -2208*a(n-8) +2048*a(n-9) -1920*a(n-10) +1536*a(n-11) -512*a(n-12) for n>15
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EXAMPLE
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Some solutions for n=4
..0..0..1..0. .0..1..2..1. .0..0..0..1. .0..1..1..1. .0..1..2..2
..2..2..0..2. .2..0..0..0. .0..2..1..1. .1..2..2..0. .1..1..0..2
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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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