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A007711
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Number of unreformed permutations of {1,...,n}.
(Formerly M3546)
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5
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1, 1, 4, 18, 105, 636, 4710, 38508, 352902, 3563297, 39467081, 475326930, 6198134207, 86912048471, 1305146666727, 20897040866280
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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REFERENCES
| 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.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
| A. M. Bersani, On the game Mousetrap.
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EXAMPLE
| 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
| Cf. A007709, A007712, A055459, A067950.
Sequence in context: A191365 A159666 A051827 * A020114 A009597 A060223
Adjacent sequences: A007708 A007709 A007710 * A007712 A007713 A007714
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| 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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