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A269762
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Number of n X 3 0..5 arrays with some element plus some horizontally or vertically adjacent neighbor totalling five exactly once.
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1
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60, 17520, 2624640, 326697720, 37212131520, 4022791852800, 420141188848320, 42818890099881480, 4284894917784397440, 422758967764941655440, 41241625930544770099200, 3986294332446031676572440
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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) = 184*a(n-1) - 9134*a(n-2) + 61640*a(n-3) - 112225*a(n-4) for n>5.
Empirical g.f.: 60*x*(1 + 108*x - 850*x^2 + 1554*x^3 + 225*x^4) / (1 - 92*x + 335*x^2)^2. - Colin Barker, Jan 28 2019
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EXAMPLE
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Some solutions for n=2:
..1..2..5. .0..1..4. .4..0..2. .2..4..4. .0..0..4. .5..3..0. .2..0..4
..5..4..1. .2..0..4. .3..0..5. .2..1..5. .4..1..5. .2..1..4. .1..2..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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