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A202967
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Number of arrays of 7 integers in -n..n with sum zero and adjacent elements differing in absolute value
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1
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6, 524, 9872, 66208, 289536, 941086, 2537024, 5933492, 12515772, 24295760, 44188086, 76110890, 125357152, 198686606, 304811136, 454458544, 660981870, 940393644, 1312104510, 1798910920, 2427885688, 3230300850, 4242680088
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 2*a(n-1) -a(n-2) +a(n-3) -2*a(n-5) +a(n-6) -3*a(n-7) +3*a(n-8) -a(n-9) +2*a(n-10) +a(n-11) -a(n-13) -2*a(n-14) +a(n-15) -3*a(n-16) +3*a(n-17) -a(n-18) +2*a(n-19) -a(n-21) +a(n-22) -2*a(n-23) +a(n-24)
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EXAMPLE
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Some solutions for n=4
..4....0....2...-4....3...-2...-2...-3....0...-1...-2....3....2....0....0...-4
.-2...-3....3....2....0....3...-4...-1...-1....3....3...-2....3....3....3....2
..4...-1....0...-4...-2...-1....1....0...-4....4...-4....1...-2...-1....4...-4
..0....2...-4....2....1...-3...-4....2....2....3....1....2....3...-2...-2....1
.-3....4...-2...-1...-4....0....2....1...-4...-2....0....0...-4....4...-4...-2
..1....0...-3....3...-1....4....4....2....3...-4....4...-4....0....0....2....4
.-4...-2....4....2....3...-1....3...-1....4...-3...-2....0...-2...-4...-3....3
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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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