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A251148
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Number of (n+1) X (7+1) 0..2 arrays with every 2 X 2 subblock summing to 4 and no 2 X 2 subblock having exactly two nonzero entries.
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1
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853, 1075, 1413, 1987, 2925, 4491, 7101, 11491, 18917, 31587, 53389, 91275, 157789, 275843, 487717, 872259, 1577901, 2886539, 5337725, 9971363, 18803813, 35765155, 68549453, 132276107, 256749085, 500872771, 981317541, 1929582211, 3805684077
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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) + 2*a(n-5).
Empirical g.f.: x*(853 - 1484*x - 1812*x^2 + 2013*x^3 + 1486*x^4) / ((1 - x)*(1 + x)*(1 - 2*x)*(1 - x - x^2)). - Colin Barker, Nov 26 2018
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EXAMPLE
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Some solutions for n=4:
..1..0..1..1..1..1..2..1....2..0..2..0..1..0..1..1....0..1..1..0..1..2..1..1
..2..1..2..0..2..0..1..0....1..1..1..1..2..1..2..0....2..1..1..2..1..0..1..1
..1..0..1..1..1..1..2..1....2..0..2..0..1..0..1..1....0..1..1..0..1..2..1..1
..1..2..1..1..1..1..0..1....1..1..1..1..2..1..2..0....2..1..1..2..1..0..1..1
..1..0..1..1..1..1..2..1....2..0..2..0..1..0..1..1....0..1..1..0..1..2..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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