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A228220
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Number of second differences of arrays of length 5 of numbers in 0..n.
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1
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31, 199, 625, 1429, 2731, 4651, 7309, 10825, 15319, 20911, 27721, 35869, 45475, 56659, 69541, 84241, 100879, 119575, 140449, 163621, 189211, 217339, 248125, 281689, 318151, 357631, 400249, 446125, 495379, 548131, 604501, 664609, 728575
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = 20*n^3 + 9*n^2 + 1*n + 1.
G.f.: x*(31 + 75*x + 15*x^2 - x^3) / (1 - x)^4.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n>4.
(End)
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EXAMPLE
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Some solutions for n=4:
.-2....1...-5....4....0....1....1....3...-2....4...-5...-8....4...-4....0....3
.-2...-2....6....0....2...-3....4....0....5....3....7....7...-6...-4....1...-7
.-2....5....0...-2...-5....7...-7...-2...-3...-6...-2...-2....3....4...-3....4
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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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