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A278183
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Number of n X 2 0..3 arrays with every element plus 1 mod 4 equal to some element at offset (-1,-1) (-1,0) (-1,1) (0,-1) (0,1) or (1,0), with upper left element zero.
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1
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0, 3, 28, 200, 1532, 11794, 90538, 695252, 5339294, 41003018, 314882364, 2418138526, 18570087298, 142608927356, 1095164819630, 8410314860218, 64586987065356, 495995568270926, 3808996439085090, 29251176423848812
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OFFSET
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1,2
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LINKS
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FORMULA
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Empirical: a(n) = 8*a(n-1) - 4*a(n-2) + 15*a(n-3) - 26*a(n-4) + 14*a(n-5) - 16*a(n-6).
Empirical g.f.: x^2*(3 + 4*x - 12*x^2 - x^3 - 4*x^4) / (1 - 8*x + 4*x^2 - 15*x^3 + 26*x^4 - 14*x^5 + 16*x^6). - Colin Barker, Feb 08 2019
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EXAMPLE
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Some solutions for n=4:
..0..1. .0..2. .0..2. .0..1. .0..3. .0..1. .0..3. .0..1. .0..1. .0..3
..3..2. .1..3. .1..3. .3..2. .1..2. .0..2. .1..3. .0..2. .1..2. .1..0
..2..1. .2..0. .1..0. .3..1. .1..0. .3..3. .2..0. .1..3. .0..3. .2..0
..1..1. .3..2. .2..3. .0..3. .3..3. .2..1. .1..0. .3..0. .1..2. .3..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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