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A221022
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Equals one maps: number of n X 4 binary arrays indicating the locations of corresponding elements equal to exactly one of their horizontal, vertical and antidiagonal neighbors in a random 0..3 n X 4 array.
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1
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8, 168, 3474, 62944, 1038208, 16735744, 268269568, 4294303744, 68716822528, 1099501010944, 17592143577088, 281474806841344, 4503598947893248, 72057591320018944, 1152921493735211008, 18446744030223007744
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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) = 20*a(n-1) -64*a(n-2) for n>5.
G.f.: 2*x*(4 + 4*x + 313*x^2 + 2108*x^3 + 832*x^4) / ((1 - 4*x)*(1 - 16*x)).
a(n) = 16^n - 81*2^(2*n-3) for n>3.
(End)
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EXAMPLE
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Some solutions for n=3:
..1..1..0..1....1..1..1..1....1..0..0..1....1..0..1..1....1..1..0..1
..1..1..1..1....1..1..1..1....0..0..1..1....1..0..0..1....1..0..1..1
..1..1..0..1....0..1..1..0....1..1..1..0....1..0..1..1....1..1..1..1
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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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