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Search: id:A087034
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| A087034 |
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Number of distinct values taken on by f(P)=Sum[p(i)p(n+1-i),i=1..n] as {p(1),p(2),...,p(n)} ranges over all permutations P of {1,2,3,...n}. |
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+0
2
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| 1, 1, 2, 3, 8, 9, 34, 35, 103, 77, 207, 138
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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See A087035 for the maximum value of f(P) as P ranges over all permutations of {1,2,3,...,n}. It appears that the corresponding minimum value of f(P) is given by A000292=C(n+3,3).
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EXAMPLE
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a(3)=2, since f takes on exactly two distinct values 10 and 13: f({1,2,3})=10, f({1,3,2)}=13, f({2,1,3})=13, f({2,3,1})=13, f({3,1,2})=13, and f({3,2,1})=10.
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CROSSREFS
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Cf. A000292, A087035.
Adjacent sequences: A087031 A087032 A087033 this_sequence A087035 A087036 A087037
Sequence in context: A030439 A119386 A140484 this_sequence A133165 A019307 A028742
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KEYWORD
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nonn
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AUTHOR
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John W. Layman (layman(AT)math.vt.edu), Jul 31 2003
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