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A268968
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Number of n X 5 0..2 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once.
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1
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144, 3312, 63792, 1125360, 18852912, 305242992, 4823705520, 74858700528, 1145496747312, 17332683832944, 259866681636528, 3866483993274864, 57157824214772784, 840294622720295280, 12294351113071353264
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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) = 30*a(n-1) - 261*a(n-2) + 540*a(n-3) - 324*a(n-4).
Empirical g.f.: 144*x*(1 - 7*x + 14*x^2 - 12*x^3) / (1 - 15*x + 18*x^2)^2. - Colin Barker, Jan 17 2019
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EXAMPLE
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Some solutions for n=3:
..0..1..2..0..1. .0..2..2..2..1. .1..0..1..0..0. .0..2..1..0..1
..2..2..1..0..0. .2..2..1..0..0. .1..0..0..1..0. .1..0..1..2..2
..1..0..0..1..2. .1..0..0..0..1. .2..1..0..1..0. .1..2..2..1..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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