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 A007711 Number of unreformed permutations of {1,...,n}. (Formerly M3546) 5
 0, 1, 4, 18, 105, 636, 4710, 38508, 352902, 3563297, 39467081, 475326930, 6198134207, 86912048471, 1305146666727, 20897040866280 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 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 ErdÅ‘s is Eighty. Bolyai Society Math. Studies, Vol. 1, pp. 193-206, 1993. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS A. M. Bersani, On the game Mousetrap. A. M. Bersani, Reformed Permutations in mousetrap and its generalizations, INTEGERS, 10 (2010), #G01. R. K. Guy and R. J. Nowakowski, Mousetrap, Preprint, Feb 10 1993 [Annotated scanned copy] R. K. Guy and R. J. Nowakowski, Mousetrap, Amer. Math. Monthly, 101 (1994), 1007-1010. FORMULA a(n) = n! - A007709(n). - Sean A. Irvine, Jan 17 2018 EXAMPLE For n=3, the 4 unreformed permutations are 123, 231, 312, 213, so a(3)=4. Also 132->123, 321->213 are reformable. CROSSREFS Cf. A007709, A007712, A055459, A067950. Sequence in context: A316186 A231274 A051827 * A321278 A020114 A009597 Adjacent sequences:  A007708 A007709 A007710 * A007712 A007713 A007714 KEYWORD nonn,more AUTHOR 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 a(1) corrected by Joerg Arndt, Dec 24 2014 STATUS approved

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Last modified June 7 05:20 EDT 2020. Contains 334837 sequences. (Running on oeis4.)