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A183982
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1/4 the number of (n+1) X 6 binary arrays with all 2 X 2 subblock sums the same.
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1
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25, 27, 30, 36, 46, 66, 102, 174, 310, 582, 1110, 2166, 4246, 8406, 16662, 33174, 66070, 131862, 263190, 525846, 1050646, 2100246, 4198422, 8394774, 16785430, 33566742, 67125270, 134242326, 268468246, 536920086, 1073807382, 2147581974, 4295098390
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OFFSET
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1,1
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COMMENTS
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Column 5 of A183986.
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..200
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FORMULA
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Empirical: a(n) = 3*a(n-1) - 6*a(n-3) + 4*a(n-4).
Conjectures from Colin Barker, Apr 08 2018: (Start)
G.f.: x*(25 - 48*x - 51*x^2 + 96*x^3) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)).
a(n) = 3*2^(n/2-1) + 2^(n-1) + 22 for n even.
a(n) = 2^(n-1) + 2^((n+1)/2) + 22 for n odd.
(End)
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EXAMPLE
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Some solutions for 5 X 6:
..0..1..1..0..1..0....0..1..1..1..0..1....0..1..0..0..1..0....0..1..0..1..1..1
..1..0..0..1..0..1....1..1..0..1..1..1....1..0..1..1..0..1....1..0..1..0..0..0
..0..1..1..0..1..0....0..1..1..1..0..1....0..1..0..0..1..0....0..1..0..1..1..1
..1..0..0..1..0..1....1..1..0..1..1..1....1..0..1..1..0..1....1..0..1..0..0..0
..0..1..1..0..1..0....0..1..1..1..0..1....0..1..0..0..1..0....0..1..0..1..1..1
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CROSSREFS
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Cf. A183986.
Sequence in context: A157091 A070662 A350181 * A287763 A239523 A361821
Adjacent sequences: A183979 A183980 A183981 * A183983 A183984 A183985
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Jan 08 2011
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STATUS
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approved
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