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A224672
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Number of (n+1) X 5 0..2 matrices with each 2 X 2 subblock idempotent.
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1
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70, 123, 170, 260, 381, 573, 864, 1322, 2043, 3191, 5026, 7972, 12713, 20357, 32696, 52630, 84851, 136951, 221214, 357516, 578017, 934753, 1511920, 2445750, 3956671, 6401343, 10356854, 16756952, 27112473, 43868001, 70978956, 114845342
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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*(70 - 157*x + 28*x^2 + 125*x^3 - 72*x^4 + 3*x^5) / ((1 - x)^3*(1 - x - x^2)). - Colin Barker, Feb 17 2018
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EXAMPLE
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Some solutions for n=3:
..0..0..1..0..0....1..1..0..1..0....0..1..0..0..0....1..0..0..0..1
..0..0..1..0..0....0..0..0..1..0....0..1..0..0..0....1..0..0..0..1
..0..0..1..0..1....0..0..0..1..0....0..1..0..0..0....0..0..0..0..1
..0..0..1..0..1....0..0..0..1..0....0..1..0..0..1....0..0..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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