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A296719
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Number of n X 2 0..1 arrays with each 1 adjacent to 0, 2 or 4 king-move neighboring 1s.
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1
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3, 9, 21, 57, 153, 393, 1041, 2745, 7185, 18921, 49761, 130713, 343761, 903753, 2375553, 6245625, 16419249, 43163817, 113476065, 298319193, 784254225, 2061749001, 5420172609, 14249195961, 37460035185, 98479462761, 258894708897
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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) = a(n-1) + 2*a(n-2) + 6*a(n-3).
Empirical g.f.: 3*x*(1 + 2*x + 2*x^2) / (1 - x - 2*x^2 - 6*x^3).
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EXAMPLE
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Some solutions for n=5:
..0..0. .1..0. .1..1. .0..1. .1..0. .0..0. .0..0. .0..1. .0..1. .0..0
..0..1. .1..1. .0..1. .1..1. .1..1. .0..0. .0..0. .1..1. .1..1. .1..1
..0..0. .1..1. .1..1. .1..1. .0..0. .0..0. .1..0. .1..1. .0..0. .1..0
..0..0. .0..1. .0..0. .1..0. .1..1. .0..1. .0..0. .0..1. .0..1. .1..1
..0..1. .0..0. .1..0. .0..0. .0..1. .0..0. .0..1. .1..1. .0..0. .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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