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A213119
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Number of binary arrays of length 2*n+1 with fewer than n ones in any length 2n subsequence (=less than 50% duty cycle).
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1
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1, 7, 34, 151, 646, 2710, 11236, 46231, 189214, 771442, 3136156, 12720982, 51507964, 208260556, 841065544, 3393346711, 13679459854, 55106773786, 221860011244, 892741834546, 3590659699444, 14436037598836, 58018598086264
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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Recurrence: n*a(n) = 2*(4*n-3)*a(n-1) - 8*(2*n-3)*a(n-2). - Vaclav Kotesovec, Oct 19 2012
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EXAMPLE
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Some solutions for n=3
..0....0....1....1....0....1....1....0....1....1....0....0....0....0....0....0
..0....1....0....0....0....0....0....0....0....0....1....0....0....0....0....0
..0....0....0....0....0....0....0....1....0....0....1....1....0....0....1....0
..1....0....0....0....0....0....0....0....1....0....0....1....1....1....0....0
..0....1....1....0....0....0....0....0....0....1....0....0....1....0....0....0
..1....0....0....1....1....0....1....0....0....0....0....0....0....0....0....1
..0....0....0....0....1....1....1....0....0....1....0....0....0....0....1....0
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MATHEMATICA
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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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