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A066375
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6*binomial(n,4)+3*binomial(n,3)+4*binomial(n,2)-n+2.
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1
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1, 4, 14, 40, 97, 206, 394, 694, 1145, 1792, 2686, 3884, 5449, 7450, 9962, 13066, 16849, 21404, 26830, 33232, 40721, 49414, 59434, 70910, 83977, 98776, 115454, 134164, 155065, 178322, 204106, 232594, 263969, 298420, 336142
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OFFSET
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1,2
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LINKS
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Harry J. Smith, Table of n, a(n) for n = 1..1000
M. Azaola and F. Santos, The number of triangulations of the cyclic polytope C(n,n-4), Discrete Comput. Geom., 27 (2002), 29-48.
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FORMULA
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a(n) = (8-14*n+13*n^2-4*n^3+n^4)/4. G.f.: x*(1-x+4*x^2+2*x^4)/(1-x)^5. [Colin Barker, Apr 20 2012]
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PROG
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(PARI) { for (n=1, 1000, a=6*binomial(n, 4) + 3*binomial(n, 3) + 4*binomial(n, 2) - n + 2; write("b066375.txt", n, " ", a) ) } [From Harry J. Smith, Feb 11 2010]
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CROSSREFS
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Sequence in context: A182819 A144141 A187594 * A093160 A001938 A066368
Adjacent sequences: A066372 A066373 A066374 * A066376 A066377 A066378
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane, Jan 04 2002
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STATUS
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approved
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