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A221458
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Number of 0..7 arrays of length n with each element unequal to at least one neighbor, with new values introduced in 0..7 order
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1
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0, 1, 2, 7, 25, 102, 456, 2219, 11639, 65320, 389533, 2451393, 16164044, 110866328, 785411383, 5709898562, 42358751505, 319155928942, 2433165471304, 18714220718157, 144885627697659, 1127182676182780, 8800901309557829
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OFFSET
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1,3
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 22*a(n-1) -168*a(n-2) +440*a(n-3) +421*a(n-4) -2898*a(n-5) -924*a(n-6) +7944*a(n-7) +5931*a(n-8) -6610*a(n-9) -10562*a(n-10) -5040*a(n-11) -840*a(n-12)
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EXAMPLE
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Some solutions for n=6
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..1....1....1....1....1....1....1....1....1....1....1....1....1....1....1....1
..2....1....1....2....0....2....0....0....2....1....1....0....2....2....0....2
..3....2....0....3....1....2....1....2....0....2....2....0....0....2....0....1
..0....1....0....3....2....1....2....2....3....0....2....2....1....3....2....1
..2....0....2....2....1....0....3....1....4....3....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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