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A197435
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Number of n X 1 0..2 arrays with no element equal to the average of its horizontal and vertical neighbors.
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1
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3, 6, 10, 28, 66, 164, 400, 982, 2406, 5898, 14456, 35434, 86852, 212884, 521802, 1278994, 3134954, 7684116, 18834610, 46165692, 113157168, 277360614, 679841246, 1666365362, 4084444032, 10011419722, 24539086364, 60147988628, 147429308586
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = a(n-1) +2*a(n-2) +3*a(n-3) +2*a(n-4) for n>5.
Empirical g.f.: x*(3 + 3*x - 2*x^2 - 3*x^3 - 6*x^4) / (1 - x - 2*x^2 - 3*x^3 - 2*x^4). - Colin Barker, May 12 2018
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EXAMPLE
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Some solutions for n=4:
0 2 1 0 2 1 1 1 2 2 1 2 0 0 0 0
1 0 0 2 1 2 0 2 0 0 0 1 1 2 2 2
1 0 2 0 1 0 2 0 2 1 1 2 1 1 2 0
2 1 1 1 2 1 0 2 0 0 0 0 0 2 1 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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