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A224667
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Number of 5 X 5 0..n matrices with each 2 X 2 subblock idempotent.
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1
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196, 260, 332, 412, 500, 596, 700, 812, 932, 1060, 1196, 1340, 1492, 1652, 1820, 1996, 2180, 2372, 2572, 2780, 2996, 3220, 3452, 3692, 3940, 4196, 4460, 4732, 5012, 5300, 5596, 5900, 6212, 6532, 6860, 7196, 7540, 7892, 8252, 8620, 8996, 9380, 9772, 10172
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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*n^2 + 52*n + 140.
G.f.: 4*x*(49 - 82*x + 35*x^2) / (1 - x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>3.
(End)
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EXAMPLE
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Some solutions for n=3:
..0..1..0..0..1....1..0..1..0..0....1..0..1..0..0....1..0..1..0..0
..0..1..0..0..1....1..0..1..0..1....1..0..1..0..1....1..0..1..0..0
..0..1..0..0..1....0..0..1..0..1....1..0..1..0..1....1..0..1..0..0
..0..1..0..0..1....0..0..1..0..1....1..0..1..0..1....1..0..1..0..1
..0..1..0..0..1....0..0..1..0..1....0..0..1..0..1....2..0..1..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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