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Search: id:A049031
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| A049031 |
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Maximization of sums of cubes of integer differences (b_[ i ]-i)^3 over permutations {b_[ i ], for i-1,2,...,n} on first n integers. |
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2
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| 0, 0, 2, 8, 20, 40, 80, 140, 224, 336, 504, 720, 990, 1320, 1760, 2288, 2912, 3640, 4550, 5600, 6800, 8160, 9792, 11628, 13680, 15960, 18620, 21560, 24794, 28336, 32384, 36800, 41600, 46800, 52650, 58968, 65772, 73080, 81200, 89900
(list; graph; listen)
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OFFSET
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1,3
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REFERENCES
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D. C. Blest, Optimising Sums of Cubes of Integer Differences, Math. Gaz., forthcoming (1999).
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FORMULA
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a[ n ] = (Sum_{i=1}^{i=r} [ (n+1-2i)^3-(n-r)*r^3 ]) / 3 where r=floor((n+2)/4)).
a(n) = r*(n-r+1)*(n-r)*(n-r-1)/3, where r = floor((n+1)/4). - Vladeta Jovovic (vladeta(AT)Eunet.yu), Dec 22 2004
G.f.: 2*x^3*(1+2*x+3*x^2+4*x^3+7*x^4+4*x^5+3*x^6+2*x^7+x^8)/((1+x)^3*(1+x^2)^3*(1-x)^5). - Vladeta Jovovic (vladeta(AT)Eunet.yu), Dec 22 2004
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CROSSREFS
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Cf. A049032.
Sequence in context: A032767 A032633 A007290 this_sequence A058037 A048096 A072250
Adjacent sequences: A049028 A049029 A049030 this_sequence A049032 A049033 A049034
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KEYWORD
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nonn,nice,easy
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AUTHOR
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David C Blest (D.Blest(AT)utas.edu.au)
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