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A262912
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Number of (n+1)X(3+1) 0..1 arrays with each row divisible by 3 and each column divisible by 7, read as a binary number with top and left being the most significant bits.
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1
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1, 6, 15, 53, 318, 1207, 5797, 34782, 189135, 1089701, 6538206, 38547751, 229660021, 1377960126, 8242589055, 49395098933, 296370593598, 1777250964247, 10661181588037, 63967089528222, 383764138693935, 2302493636842181
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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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Empirical: a(n) = 8*a(n-1) -16*a(n-2) +104*a(n-3) -640*a(n-4) +1280*a(n-5) -3830*a(n-6) +15280*a(n-7) -30560*a(n-8) +58240*a(n-9) -99200*a(n-10) +198400*a(n-11) -283209*a(n-12) -115128*a(n-13) +230256*a(n-14) -345384*a(n-15).
Empirical formula verified: see link. - Robert Israel, Aug 12 2019
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EXAMPLE
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Some solutions for n=4
..1..1..0..0....0..0..0..0....0..1..1..0....0..0..0..0....0..1..1..0
..1..1..1..1....0..0..0..0....1..0..0..1....0..1..1..0....0..0..0..0
..1..1..1..1....0..0..0..0....1..1..1..1....0..1..1..0....0..1..1..0
..0..0..1..1....0..0..0..0....1..0..0..1....0..1..1..0....0..0..0..0
..0..0..0..0....0..0..0..0....0..1..1..0....0..0..0..0....0..1..1..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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