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A006473
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C(n,2)!/n!.
(Formerly M5217)
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0
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1, 30, 30240, 1816214400, 10137091700736000, 7561714896123855667200000, 1025113885554181044609786839040000000, 32964677266721834921175915315161407370035200000000, 318071672921132854486459356650996997744817246158245068800000000000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 3,2
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COMMENTS
| a(n) is also the number of distinct possible (n-1)-dimensional simplex if the (n-1)*n/2 1-faces are given (up to symmetry, rotation, reflection). - Dan Dima, Nov 03 2011
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REFERENCES
| O. Frank and K. Svensson, On probability distributions of single-linkage dendrograms, Journal of Statistical Computation and Simulation, 12 (1981), 121-131.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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EXAMPLE
| a(3)=1 since there is one possible triangle if the 3 edges are given and a(4)=30 since there are 30 distinct possible tetrahedron if the 6 edges are given. - Dan Dima, Nov 03 2011
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CROSSREFS
| Sequence in context: A088853 A135349 A159373 * A115459 A135421 A028668
Adjacent sequences: A006470 A006471 A006472 * A006474 A006475 A006476
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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