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A251271
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Number of (4+1) X (n+1) 0..1 arrays with no 2 X 2 subblock having x11-x00 less than x10-x01.
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1
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337, 2058, 9109, 32636, 100843, 279718, 715685, 1722176, 3954037, 8757506, 18871133, 39828260, 82762159, 170015870, 346360653, 701430696, 1414589161, 2844655514, 5709353797, 11444200908, 22920272755, 45879723734, 91806810133
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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) = 11*a(n-1) - 54*a(n-2) + 156*a(n-3) - 294*a(n-4) + 378*a(n-5) - 336*a(n-6) + 204*a(n-7) - 81*a(n-8) + 19*a(n-9) - 2*a(n-10).
G.f.: x*(337 - 1649*x + 4669*x^2 - 9003*x^3 + 11763*x^4 - 10549*x^5 + 6447*x^6 - 2573*x^7 + 606*x^8 - 64*x^9) / ((1 - x)^9*(1 - 2*x)).
a(n) = (20160*(1369*2^n-1365) - 18907464*n - 6363848*n^2 - 1352064*n^3 - 190036*n^4 - 16401*n^5 - 637*n^6 + 9*n^7 + n^8) / 2520.
(End)
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EXAMPLE
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Some solutions for n=4:
..0..0..0..0..0....0..1..0..0..0....0..0..0..0..0....1..0..1..0..1
..0..0..0..0..1....0..0..1..1..1....1..1..1..1..1....0..1..0..1..1
..0..0..0..1..1....0..0..0..1..1....0..1..1..1..1....0..0..1..1..1
..0..1..1..0..0....0..0..0..1..1....0..0..0..1..1....1..1..0..0..0
..0..0..0..1..1....0..1..1..0..0....0..1..1..0..0....0..0..1..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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