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A264515
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Number of (n+1)X(3+1) arrays of permutations of 0..n*4+3 with each element having directed index change -1,0 0,2 -1,-2 or 1,0.
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1
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1, 1, 9, 36, 144, 576, 2116, 8281, 31329, 121801, 467856, 1809025, 6969600, 26884225, 103632400, 399560121, 1540484001, 5939322489, 22899558276, 88289802496, 340406901136, 1312449766884, 5060209759081, 19509827162049, 75220946346001
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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) = 3*a(n-1) +7*a(n-2) -17*a(n-3) -5*a(n-4) +60*a(n-5) +8*a(n-6) -24*a(n-7) -36*a(n-8) +36*a(n-11) +24*a(n-12) -8*a(n-13) -60*a(n-14) +5*a(n-15) +17*a(n-16) -7*a(n-17) -3*a(n-18) +a(n-19)
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EXAMPLE
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Some solutions for n=4
..4..5..0..7....4..5..0..1....4..5..6..7....6..5..0..1....4..7..0..1
..8..1..2..3....8.11..2..3....0..1..2..3...10.11..2..3...10.11..2..3
.14.15..6..9...14.15..6..7...14.15..8..9....4.15..8..7...14..5..6..9
.18.19.10.11...18..9.10.19...18.19.10.11...16..9.18.19....8.17.18.19
.12.13.16.17...12.13.16.17...12.13.16.17...12.13.14.17...12.13.16.15
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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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