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A040018
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(Number of permutations of {1,2,...n} for which sums of adjacent numbers are all distinct)/2n.
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4
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1, 1, 3, 8, 46, 176, 955, 5446, 36122, 259084, 2043944
(list; graph; refs; listen; history; internal format)
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OFFSET
| 3,3
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COMMENTS
| Essentially different ways 1,2,3,...n can be placed around a circle so that sums of adjacent numbers are distinct.
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CROSSREFS
| Cf. A091217, A006967.
Sequence in context: A000240 A132103 A180508 * A019016 A063859 A034183
Adjacent sequences: A040015 A040016 A040017 * A040019 A040020 A040021
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KEYWORD
| hard,nonn,changed
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AUTHOR
| Erich Friedman (erich.friedman(AT)stetson.edu)
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EXTENSIONS
| One more term from Vladeta Jovovic, Aug 25 2007
Three more terms from Steve Butler, Feb 08 2012
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