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A200252
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Number of 0..n arrays x(0..2) of 3 elements with each no smaller than the sum of its previous elements modulo (n+1).
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5
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5, 12, 26, 45, 75, 112, 164, 225, 305, 396, 510, 637, 791, 960, 1160, 1377, 1629, 1900, 2210, 2541, 2915, 3312, 3756, 4225, 4745, 5292, 5894, 6525, 7215, 7936, 8720, 9537, 10421, 11340, 12330, 13357, 14459, 15600, 16820, 18081, 19425, 20812, 22286, 23805
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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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a(n) = 2*a(n-1) + a(n-2) - 4*a(n-3) + a(n-4) + 2*a(n-5) - a(n-6).
G.f.: x*(5 + 2*x - 3*x^2 + x^3 + 2*x^4 - x^5) / ((1 - x)^4*(1 + x)^2).
a(n) = (n^3 + 5*n^2 + 8*n + 4) / 4 for n even.
a(n) = (n^3 + 5*n^2 + 9*n + 5) / 4 for n odd.
(End)
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EXAMPLE
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Some solutions for n=6:
2 0 0 3 3 1 4 0 1 3 0 3 0 2 1 3
6 5 3 6 3 1 5 2 4 6 6 5 0 5 2 4
2 6 6 2 6 4 4 2 6 5 6 5 6 5 4 0
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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