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A275566
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Number of 3 X n 0..2 arrays with no element equal to any value at offset (-2,0) (-1,2) or (0,-2) and new values introduced in order 0..2.
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1
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3, 54, 126, 294, 672, 1536, 3552, 8214, 19092, 44376, 103200, 240000, 558000, 1297350, 3015990, 7011366, 16299318, 37891014, 88085676, 204773784, 476041212, 1106661366, 2572675992, 5980747104, 13903551072, 32321836896, 75139155000
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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) = 3*a(n-1) - 5*a(n-3) + a(n-4) + 7*a(n-5) - 5*a(n-6) + 2*a(n-8) - a(n-9) for n>10.
Empirical g.f.: 3*x*(1 + 15*x - 12*x^2 - 23*x^3 + 19*x^4 + 25*x^5 - 25*x^6 + 4*x^7 + 8*x^8 - 5*x^9) / ((1 - 3*x + 2*x^2 - x^3)*(1 - 2*x^2 + 3*x^4 - x^6)). - Colin Barker, Feb 04 2019
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EXAMPLE
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Some solutions for n=4:
..0..0..1..1. .0..1..2..0. .0..1..2..0. .0..0..1..1. .0..1..2..0
..2..0..0..2. .1..2..2..0. .0..2..2..1. .0..2..2..0. .1..2..0..1
..1..1..2..2. .1..2..0..1. .1..2..0..1. .1..1..0..2. .2..0..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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