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Search: id:A007711
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| A007711 |
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Number of unreformed permutations of {1,...,n}.
(Formerly M3546)
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+0
6
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| 1, 1, 4, 18, 105, 636, 4710, 38508, 352902, 3563297, 39467081, 475326930, 6198134207, 86912048471, 1305146666727, 20897040866280
(list; graph; listen)
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OFFSET
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1,3
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
A. M. Bersani, "Reformed permutations in Mousetrap and its generalizations", preprint MeMoMat n. 15/2005.
R. K. Guy and R. J. Nowakowski, ``Mousetrap,'' in D. Miklos, V.T. Sos and T. Szonyi, eds., Combinatorics, Paul Erdos is Eighty. Bolyai Society Math. Studies, Vol. 1, pp. 193-206, 1993.
R. K. Guy and R. J. Nowakowski, ``Mousetrap,'' Amer. Math. Monthly, 101 (1994), 1007-1010.
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LINKS
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A. M. Bersani, On the game Mousetrap.
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EXAMPLE
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For n=3 the 4 unreformed permutations are 123,231,312,213. So a(3)=4 Also 132->123, 321->213 are reformable.
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CROSSREFS
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Cf. A007709, A007712, A055459, A067950.
Sequence in context: A064852 A159666 A051827 this_sequence A020114 A009597 A060223
Adjacent sequences: A007708 A007709 A007710 this_sequence A007712 A007713 A007714
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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).
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EXTENSIONS
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More terms from Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), Mar 06 2002
2 more terms from Alberto M. Bersani (bersani(AT)dmmm.uniroma1.it), Feb 07 2007
One more term from Alberto M. Bersani (bersani(AT)dmmm.uniroma1.it), Feb 24 2008
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