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Search: id:A018934
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| A018934 |
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From the game of Mousetrap. |
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+0
2
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| 0, 0, 0, 2, 8, 42, 256, 1810, 14568, 131642, 1320128, 14551074, 174879880, 2276108362, 31894886208, 478775722802, 7664993150696, 130369025763930, 2347604596782208, 44619881467365442, 892659329531868168
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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Number of permutations p of [n] such that p(k) = k+2 for exactly one k in the range 0<k<n-1. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Nov 30 2007
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REFERENCES
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Mundfrom, Daniel J.; A problem in permutations: the game of `Mousetrap'. European J. Combin. 15 (1994), no. 6, 555-560.
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FORMULA
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a(n) = (n-2)*A055790(n-2). E.g.f.: 2*x*exp(-x)/(1-x)^3. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Nov 30 2007
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CROSSREFS
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Cf. A002468.
Sequence in context: A120916 A133417 A100327 this_sequence A107588 A013999 A130649
Adjacent sequences: A018931 A018932 A018933 this_sequence A018935 A018936 A018937
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KEYWORD
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nonn
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AUTHOR
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njas
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EXTENSIONS
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More terms from Vladeta Jovovic (vladeta(AT)Eunet.yu), Nov 30 2007, corrected Jan 25 2008
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