Search: id:A060008
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%I A060008
%S A060008 0,0,0,0,9,45,135,315,630,1134,1890,2970,4455,6435,9009,12285,16380,
%T A060008 21420,27540,34884,43605,53865,65835,79695,95634,113850,134550,157950,
%U A060008 184275,213759,246645,283185,323640,368280,417384,471240,530145,594405
%N A060008 9*C(n,4) = 3n(n-1)(n-2)(n-3)/8
%C A060008 Number of permutations of n letters where exactly four change position.
%C A060008 Number of permutations of (4 to infinity) distinct letters (ABC......XYW 
               etc.) each with 1 copies such that there are n-4 fixed points. - 
               Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 15 2006
%H A060008 Harry J. Smith, <a href="b060008.txt">Table of n, a(n) for n=0,...,1000</
               a>
%F A060008 Equals 3*A050534. - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Feb 
               12 2007
%e A060008 a(6) = 135 since there are 15 ways to choose the four points that move 
               and 9 ways to move them and 15*9=135.
%o A060008 (PARI) { for (n=0, 1000, write("b060008.txt", n, " ", 3*n*(n - 1)*(n 
               - 2)*(n - 3)/8); ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), 
               Jul 01 2009]
%Y A060008 For changing 0, 1, 2, 3, 4, 5, n-4, n elements see A000012, A000004, 
               A000217 (offset), A007290, A060008, A060836, A000475, A000166. Also 
               see A000332, A008290.
%Y A060008 A diagonal of A008291.
%Y A060008 Sequence in context: A139609 A068314 A152996 this_sequence A095166 A126899 
               A008501
%Y A060008 Adjacent sequences: A060005 A060006 A060007 this_sequence A060009 A060010 
               A060011
%K A060008 easy,nonn
%O A060008 0,5
%A A060008 Henry Bottomley (se16(AT)btinternet.com), Mar 16 2001

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