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A006967
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Number of graceful permutations of length n.
(Formerly M3229)
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7
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1, 2, 4, 4, 8, 24, 32, 40, 120, 296, 648, 1328, 3200, 9912, 25592, 55920, 143192, 510696, 1451296, 3497344, 10451824, 38570704, 118914992, 315235872, 1014824752, 3963684496, 13166130152, 37846301904, 130507967088
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| n! - A084894(n). - Jon Perry, Jun 10 2003
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REFERENCES
| N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
H. S. Wilf and N. Yoshimura, Ranking rooted trees and a graceful application, in Discrete Algorithms and Complexity (Proceedings of the Japan-US joint seminar, 1986, Kyoto, Japan), edited by D. Johnson, T. Nishizeki, A. Nozaki and H. S. Wilf, Academic Press, NY, 1987, pp. 341-350.
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LINKS
| Michal Adamaszek (aszek(AT)mimuw.edu.pl), Aug 22 2006, Table of n, a(n) for n = 1..40
Eric Weisstein's World of Mathematics, Graceful Permutation
M. Adamaszek, Efficient enumeration of graceful permutations
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CROSSREFS
| Sequence in context: A161816 A160124 A080007 * A122033 A201777 A096189
Adjacent sequences: A006964 A006965 A006966 * A006968 A006969 A006970
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KEYWORD
| nonn,nice,hard
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| n=2 term corrected 6/96. a(11)-a(20) from Robert Aldred and Brendan McKay (bdm(AT)cs.anu.edu.au).
More terms from Michal Adamaszek (aszek(AT)mimuw.edu.pl), Aug 22 2006
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