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A011894
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[ n(n-1)(n-2)/12 ].
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0
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0, 0, 0, 0, 2, 5, 10, 17, 28, 42, 60, 82, 110, 143, 182, 227, 280, 340, 408, 484, 570, 665, 770, 885, 1012, 1150, 1300, 1462, 1638, 1827, 2030, 2247, 2480, 2728, 2992, 3272, 3570, 3885, 4218, 4569, 4940
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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COMMENTS
| a(n+1)=floor[(n^3-n)/12] is an upper bound for the Kirchhoff index of a circulant graph with n vertices [Zhang&Yang] - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 26 2007
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LINKS
| H. Zhang and Y. Yang, Resistance Distance and Kirchhoff Index in Circulant Graphs, Int. J. Quant. Chem. 107 (2007) 330-339.
Index to sequences with linear recurrences with constant coefficients, signature (3,-3,1,1,-3,3,-1). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 15 2010]
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FORMULA
| a(n) = +3*a(n-1) -3*a(n-2) +a(n-3) +a(n-4) -3*a(n-5) +3*a(n-6) -a(n-7). G.f.: x^4*(-x+x^2+2) / ( (-1+x)^4*(1+x)*(x^2+1) ). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 15 2010]
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MAPLE
| seq(floor(binomial(n, 3)/2), n=0..40); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jan 12 2009]
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PROG
| (Other) sage: [floor(binomial(n, 3)/2) for n in xrange(0, 41)]# [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Dec 01 2009]
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CROSSREFS
| Sequence in context: A172059 A172435 A049688 * A172512 A172982 A178137
Adjacent sequences: A011891 A011892 A011893 * A011895 A011896 A011897
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| Removed duplicate of the Maple program - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 25 2009
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