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Search: id:A105927
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| A105927 |
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Let d(n) = A000166(n); then a(n) = (n^2+n-1)*d(n) + (-1)^(n-1)*(n-1). |
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+0
2
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| 0, 0, 2, 12, 84, 640, 5430, 50988, 526568, 5940576, 72755370, 961839340, 13656650172, 207316760352, 3351430059614, 57487448630220, 1042952206111440, 19954639072648768, 401578933206288978, 8480263630552747596, 187505565234912994340, 4332318322289242716480
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OFFSET
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0,3
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COMMENT
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Number of permutations p of [n] such that p(k) = k+2 for exactly two k in the range 0<k<n-1, (offset 2). - Vladeta Jovovic (vladeta(AT)eunet.rs), Dec 14 2007
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REFERENCES
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P. A. MacMahon, Combinatory Analysis, 2 vols., Chelsea, NY, 1960, see p. 108.
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CROSSREFS
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Cf. A055790, A018934, A000153.
Sequence in context: A052864 A130464 A006657 this_sequence A052887 A052867 A097237
Adjacent sequences: A105924 A105925 A105926 this_sequence A105928 A105929 A105930
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Apr 27 2005
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