Search: id:A006932
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%I A006932 M2862
%S A006932 1,1,3,10,43,223,1364,9643,77545,699954,7013079,77261803,928420028,
%T A006932 12085410927,169413357149,2544367949634,40758600588283,693684669653911,
%U A006932 12499734669634036,237734433597317987,4759174459355303521
%N A006932 Number of permutations of [n] with at least one strong fixed point (a 
               permutation p of {1,2,...,n} is said to have j as a strong fixed 
               point if p(k)<j for k<j and p(k)>j for k>j).
%D A006932 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A006932 Problem E3467, Amer. Math. Monthly, 100 (1993), 800-801.
%D A006932 Stanley, R. P., Enumerative Combinatorics, Volume 1 (1986), p. 49.
%D A006932 K. Wayland, personal communication.
%H A006932 V. Strehl, <a href="a003149.pdf">The average number of splitters in a 
               random permutation</a> [Unpublished; included here with the author's 
               permission.]
%p A006932 t1 := sum(n!*x^n, n=0..100): F := series(t1/(1+x*t1), x, 100): for i 
               from 1 to 40 do printf(`%d, `, i!-coeff(F, x, i)) od:
%Y A006932 Cf. A052186.
%Y A006932 Sequence in context: A030833 A157313 A030971 this_sequence A001040 A162286 
               A032269
%Y A006932 Adjacent sequences: A006929 A006930 A006931 this_sequence A006933 A006934 
               A006935
%K A006932 nonn,easy,nice
%O A006932 1,3
%A A006932 N. J. A. Sloane (njas(AT)research.att.com).
%E A006932 More terms and Maple code from James A. Sellers (sellersj(AT)math.psu.edu), 
               Mar 13 2000
%E A006932 Edited by Emeric Deutsch, Oct 29 2008

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