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A280400
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Number of 2Xn 0..2 arrays with no element unequal to a strict majority of its horizontal and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.
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1
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0, 2, 6, 16, 34, 76, 158, 336, 698, 1460, 3030, 6296, 13042, 27004, 55822, 115296, 237866, 490308, 1009734, 2077736, 4271970, 8776972, 18019966, 36972016, 75808154, 155344596, 318145718, 651204536, 1332235218, 2724122780, 5567550190
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 3*a(n-1) +a(n-2) -7*a(n-3) +4*a(n-5).
Empirical g.f.: 2*x^2*(-1+2*x^2+3*x^3) / ( (x-1)*(1+x)^2*(2*x-1)^2 ). - R. J. Mathar, Jan 04 2017
Empirical: a(n) = 2^(n-1)*n/9 +2^(n-1)*47/27 +(-1)^n*2*n/9 -10*(-1)^n/27-2. - R. J. Mathar, Jan 04 2017
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EXAMPLE
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Some solutions for n=4
..0..0..0..0. .0..1..1..1. .0..0..1..0. .0..0..1..1. .0..0..0..0
..0..0..1..1. .1..1..1..1. .0..0..0..0. .0..1..1..2. .0..1..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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