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A202117
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Number of -1..1 arrays of n elements with first, second and third differences also in -1..1
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1
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3, 7, 13, 19, 27, 35, 47, 65, 91, 129, 185, 267, 387, 563, 821, 1199, 1753, 2565, 3755, 5499, 8055, 11801, 17291, 25337, 37129, 54411, 79739, 116859, 171261, 250991, 367841, 539093, 790075, 1157907, 1696991, 2487057, 3644955, 5341937, 7828985
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OFFSET
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1,1
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COMMENTS
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Column 1 of A202124
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..210
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FORMULA
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Empirical: a(n) = 2*a(n-1) -a(n-2) +a(n-3) -a(n-4) for n>8
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EXAMPLE
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Some solutions for n=7
..1....1....1....0....1....1....0....0....1....1...-1...-1...-1....1...-1....0
..1....0....1...-1....0....1...-1....1....1....1....0...-1...-1....0....0....0
..1...-1....1...-1....0....0...-1....1....1....1....0...-1....0....0....1....0
..1...-1....1....0....0...-1...-1....1....1....0....0...-1....1....0....1....0
..1....0....1....1....0...-1...-1....0....0...-1....0...-1....1....0....1....0
..1....1....1....1....0....0....0...-1...-1...-1....0...-1....0....0....1....0
..0....1....1....0...-1....1....1...-1...-1...-1....1...-1...-1....0....0....0
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CROSSREFS
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Sequence in context: A144917 A102828 A117679 * A100458 A193765 A000960
Adjacent sequences: A202114 A202115 A202116 * A202118 A202119 A202120
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin Dec 11 2011
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STATUS
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approved
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