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A251286
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Number of (n+1) X (2+1) 0..1 arrays with every 2 X 2 subblock having a single 1 or two 1s on the same edge or main diagonally.
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1
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22, 71, 219, 701, 2193, 6980, 21966, 69681, 219860, 696284, 2199557, 6960357, 21999804, 69591126, 220014756, 695843558, 2200194145, 6958021138, 22001843859, 69577286765, 220014836192, 695749296057, 2200100105526, 6957283657381
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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) = 2*a(n-1) + 7*a(n-2) - 9*a(n-3) - 7*a(n-4) + 7*a(n-5) for n>6.
Empirical g.f.: x*(22 + 27*x - 77*x^2 - 36*x^3 + 51*x^4 + x^5) / (1 - 2*x - 7*x^2 + 9*x^3 + 7*x^4 - 7*x^5). - Colin Barker, Nov 28 2018
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EXAMPLE
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Some solutions for n=4:
..0..1..1....1..1..0....1..1..1....0..0..1....0..0..0....1..1..1....1..1..1
..0..0..0....0..0..0....0..0..0....1..0..0....0..1..0....0..0..0....0..0..0
..1..0..1....0..1..0....1..1..0....0..1..0....0..0..1....1..1..0....0..1..1
..1..0..1....0..0..0....0..0..0....0..0..1....1..0..0....0..0..1....0..0..0
..1..0..0....0..1..1....0..1..0....1..0..0....0..1..1....1..0..0....1..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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