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A258548
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Number of (n+1) X (2+1) 0..1 arrays with every 2 X 2 subblock ne-sw antidiagonal difference nondecreasing horizontally and nw+se diagonal sum nondecreasing vertically.
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1
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44, 112, 296, 652, 1329, 2530, 4667, 8419, 14932, 26184, 45561, 78903, 136170, 234461, 403075, 692272, 1188185, 2038466, 3496239, 5995441, 10279967, 17625041, 30216773, 51802782, 88807568, 152244537, 260993810, 447421309, 767011467
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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) = 4*a(n-1) - 5*a(n-2) + a(n-3) + 3*a(n-4) - 4*a(n-5) + 2*a(n-6) + 2*a(n-7) - 3*a(n-8) + a(n-9) for n>11.
Empirical g.f.: x*(44 - 64*x + 68*x^2 - 16*x^3 - 43*x^4 + 18*x^5 + 12*x^6 - 12*x^7 - 2*x^8 + 6*x^9 - x^10) / ((1 - x)^3*(1 - x - x^2 - x^4 + x^6)). - Colin Barker, Dec 21 2018
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EXAMPLE
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Some solutions for n=4:
..0..0..1....1..1..1....0..0..0....0..0..1....0..0..1....0..0..0....1..0..0
..0..0..0....0..0..0....1..1..1....1..0..1....1..0..1....0..0..1....0..0..0
..1..0..1....1..1..1....0..0..0....1..0..1....1..0..1....0..0..1....1..1..0
..1..0..1....1..0..0....1..1..1....0..0..1....1..0..1....1..1..1....1..0..0
..0..0..1....1..1..1....1..0..1....1..1..1....0..1..1....1..1..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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