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A183774
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Half the number of (n+1)X2 binary arrays with no 2X2 subblock having exactly 2 ones
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1
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5, 13, 33, 85, 217, 557, 1425, 3653, 9353, 23965, 61377, 157237, 402745, 1031693, 2642673, 6769445, 17340137, 44417917, 113778465, 291450133, 746563993, 1912364525, 4898620497, 12548078597, 32142560585, 82334874973, 210905117313
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OFFSET
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1,1
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COMMENTS
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a(n) appears to be sum of the elements of the n-th power of the matrix {{1, 2}, {2, 0}}. - Griffin N. Macris, Mar 25 2016
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LINKS
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FORMULA
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Empirical: a(n) = a(n-1) + 4*a(n-2).
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EXAMPLE
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Some solutions with a(1,1)=0 for 3X2
..0..1....0..0....0..1....0..1....0..1....0..0....0..0....0..1....0..0....0..0
..1..1....0..1....1..1....0..0....0..0....0..1....1..0....1..1....0..0....1..0
..1..1....0..0....1..0....1..0....0..0....1..1....1..1....0..1....0..0....0..0
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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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