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Search: id:A006245
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| A006245 |
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Number of primitive sorting networks on n elements; also number of rhombic tilings of 2n-gon.
(Formerly M1894)
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+0
15
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| 1, 1, 2, 8, 62, 908, 24698, 1232944, 112018190, 18410581880, 5449192389984
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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Also a(n) = denominator of amazing polynomial of genus 1 and level n for m = 5 = A[1,n](5) (cf. A145662). - Artur Jasinski (grafix(AT)csl.pl), Oct 16 2008
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
D. E. Knuth, Axioms and hulls, Lect. Notes Comp. Sci., Vol. 606.
K. Yamanaka, S. Nakano, Y. Matsui, R. Uehara and K. Nakada, "Efficient Enumeration of All Pseudoline Arrangements," Proc. 25th European Workshop on Computer Geometry ((EuroCG09)), pp. 143-146, 200.
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LINKS
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D. E. Knuth, Axioms and Hulls, LNCS 606 (1992) p35. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 02 2009]
M. Widom, N. Destainville, R. Mosseri and F. Bailly, Two-dimensional random tilings of large codimension
Index entries for sequences related to sorting
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CROSSREFS
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Cf. A006246.
Sequence in context: A086903 A161566 A159476 this_sequence A009271 A153539 A153567
Adjacent sequences: A006242 A006243 A006244 this_sequence A006246 A006247 A006248
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KEYWORD
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nonn,nice,more
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms from Sebastien VEIGNEAU (sv(AT)univ-mlv.fr) Jan 15 1997.
a(10) confirmed by Katsuhisa Yamanaka(<yamanaka(AT)hol.is.uec.ac.jp), May 06 2009. This value was also confirmed by Takashi Horiyama of Saitama Univ.
a(11) from Katsuhisa Yamanaka(<yamanaka(AT)hol.is.uec.ac.jp), May 06 2009.
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