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A224549
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Number of (n+1) X 8 0..1 matrices with each 2 X 2 subblock idempotent.
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1
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216, 345, 472, 682, 943, 1323, 1858, 2652, 3845, 5681, 8544, 13062, 20247, 31739, 50190, 79892, 127789, 205117, 330056, 532022, 858611, 1386835, 2241302, 3623632, 5860053, 9478413, 15332788, 24805102, 40131355, 64929471, 105053374, 169974912
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OFFSET
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1,1
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COMMENTS
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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) + 2*a(n-4) - a(n-5) for n>6.
Empirical g.f.: x*(216 - 519*x + 172*x^2 + 303*x^3 - 202*x^4 + 15*x^5) / ((1 - x)^3*(1 - x - x^2)). - Colin Barker, Aug 31 2018
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EXAMPLE
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Some solutions for n=3:
..1..1..1..0..0..1..0..0....1..0..0..0..0..0..0..0....1..1..1..0..0..0..0..0
..0..0..0..0..0..1..0..1....1..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0
..0..0..0..0..0..1..0..1....1..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0
..0..0..0..0..0..1..0..1....0..0..0..0..0..1..1..1....0..0..0..0..0..0..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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