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A235897
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Number of (n+1) X (3+1) 0..2 arrays with the minimum plus the maximum equal to the lower median plus the upper median in every 2 X 2 subblock.
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1
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473, 3265, 21697, 148945, 1030145, 7234417, 51386977, 369219409, 2679887681, 19633204273, 145044113953, 1079669229841, 8091619731713, 61015969790449, 462652793596897, 3525659262889681, 26989485570486977, 207460867269846961
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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) = 21*a(n-1) - 124*a(n-2) - 72*a(n-3) + 2128*a(n-4) - 432*a(n-5) - 12608*a(n-6) - 10752*a(n-7).
Empirical g.f.: x*(473 - 6668*x + 11784*x^2 + 132224*x^3 - 178736*x^4 - 1110848*x^5 - 870912*x^6) / ((1 + 2*x)*(1 - 6*x)*(1 - 8*x)*(1 - 6*x - 8*x^2)*(1 - 3*x - 14*x^2)). - Colin Barker, Oct 20 2018
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EXAMPLE
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Some solutions for n=4:
..0..1..2..0....1..2..1..1....0..2..1..0....1..0..2..2....1..1..0..1
..0..1..2..0....2..1..0..0....1..1..2..1....2..1..1..1....0..2..1..2
..2..1..0..2....2..1..0..0....2..0..1..2....1..2..2..2....0..2..1..0
..1..2..1..1....0..1..0..0....0..2..1..0....2..1..1..1....1..1..0..1
..2..1..0..2....1..0..1..1....1..1..0..1....1..2..0..0....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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