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A234133
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Number of (n+1) X (1+1) 0..3 arrays with every 2 X 2 subblock having the sum of the absolute values of all six edge and diagonal differences equal to 9.
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1
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32, 80, 192, 512, 1280, 3584, 9216, 26624, 69632, 204800, 540672, 1605632, 4259840, 12713984, 33816576, 101187584, 269484032, 807403520, 2151677952, 6450839552, 17196646400, 51573161984, 137506062336, 412451078144, 1099780063232
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = 2*a(n-1) + 8*a(n-2) - 16*a(n-3).
G.f.: 16*x*(2 + x - 14*x^2) / ((1 - 2*x)*(1 - 8*x^2)).
a(n) = 2^(3+n) + 2^(-1/2+(3*n)/2)*(4-4*(-1)^n + 3*sqrt(2) + 3*(-1)^n*sqrt(2)).
(End)
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EXAMPLE
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Some solutions for n=5:
3 3 0 0 0 3 3 1 3 0 1 1 0 0 3 0 3 0 3 2
0 3 0 3 3 3 0 1 3 3 0 3 3 0 3 3 0 0 0 2
1 1 0 0 0 3 1 3 0 3 0 0 1 1 3 0 3 0 2 3
0 3 0 3 0 0 0 1 3 3 3 0 0 3 0 0 0 0 0 2
2 2 2 2 0 3 3 1 0 3 1 1 2 2 0 3 3 0 2 3
0 3 0 3 0 0 0 1 3 3 3 0 0 3 2 2 1 1 2 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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