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A224668
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Number of 6 X 6 0..n matrices with each 2 X 2 subblock idempotent.
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1
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428, 542, 668, 806, 956, 1118, 1292, 1478, 1676, 1886, 2108, 2342, 2588, 2846, 3116, 3398, 3692, 3998, 4316, 4646, 4988, 5342, 5708, 6086, 6476, 6878, 7292, 7718, 8156, 8606, 9068, 9542, 10028, 10526, 11036, 11558, 12092, 12638, 13196, 13766, 14348
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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) = 6*n^2 + 96*n + 326.
G.f.: 2*x*(214 - 371*x + 163*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:
..1..0..0..0..1..0....1..1..1..1..1..0....1..0..1..0..0..3....1..0..1..0..0..1
..1..0..0..0..1..0....0..0..0..0..0..0....1..0..1..0..0..1....1..0..1..0..0..1
..1..0..0..0..1..0....1..1..1..1..1..1....0..0..1..0..0..1....1..0..1..0..0..1
..1..0..0..0..1..0....0..0..0..0..0..0....0..0..1..0..0..1....1..0..1..0..0..1
..1..0..0..0..1..0....1..1..1..1..1..1....0..0..1..0..0..1....1..0..1..0..0..1
..2..0..0..0..1..0....0..0..0..0..0..0....0..0..1..0..0..1....0..0..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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