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A255221
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Number of (n+2) X (1+2) 0..1 arrays with no 3 x 3 subblock diagonal sum 0 and no antidiagonal sum 0 and no row sum 2 and no column sum 2.
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1
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23, 22, 31, 43, 61, 88, 127, 184, 268, 391, 571, 835, 1222, 1789, 2620, 3838, 5623, 8239, 12073, 17692, 25927, 37996, 55684, 81607, 119599, 175279, 256882, 376477, 551752, 808630, 1185103, 1736851, 2545477, 3730576, 5467423, 8012896, 11743468
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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) = 2*a(n-1) - a(n-2) + a(n-3) - a(n-4) for n>5.
Empirical g.f.: x*(23 - 24*x + 10*x^2 - 20*x^3 + 7*x^4) / ((1 - x)*(1 - x - x^3)). - Colin Barker, Dec 19 2018
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EXAMPLE
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Some solutions for n=4:
..1..1..1....0..1..0....1..0..0....0..0..0....1..0..0....0..1..0....1..1..1
..1..0..0....1..1..1....1..0..0....0..0..0....1..0..0....0..1..0....0..0..1
..1..0..0....0..1..0....1..0..0....1..1..1....1..0..0....1..1..1....0..0..1
..1..1..1....0..1..0....1..0..0....0..0..0....1..0..0....0..1..0....0..0..1
..1..0..0....0..1..0....1..0..0....0..0..0....1..0..0....0..1..0....1..1..1
..1..0..0....0..1..0....1..0..0....1..1..1....1..1..1....1..1..1....0..0..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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