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A224664
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Number of n X n 0..7 matrices with each 2X2 subblock idempotent
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0
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8, 32, 200, 318, 700, 1292, 2476, 4570, 8406, 15256, 27498, 49198, 87530, 154940, 273084, 479466, 838944, 1463400, 2545472, 4416198, 7643450, 13199732, 22747870, 39126778, 67176430
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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) = 6*a(n-1) -12*a(n-2) +5*a(n-3) +12*a(n-4) -12*a(n-5) -3*a(n-6) +6*a(n-7) -a(n-9) for n>10
Empirical g.f.: 8*x -2*x^2 *(-16 -4*x +249*x^2 -516*x^3 +238*x^4 +241*x^5 -199*x^6 -31*x^7 +35*x^8) /(x-1)^3 /(x^2+x-1)^3 . - R. J. Mathar, Nov 09 2018
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EXAMPLE
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Some solutions for n=3
..1..0..0....1..0..4....1..1..6....1..1..5....1..0..0....1..0..6....1..1..2
..1..0..0....0..0..1....0..0..0....0..0..0....1..0..1....1..0..1....0..0..0
..4..0..0....0..0..1....0..1..1....0..0..1....1..0..1....2..0..1....7..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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