Search: id:A009992
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%I A009992
%S A009992 1,48,2304,110592,5308416,254803968,12230590464,587068342272,
%T A009992 28179280429056,1352605460594688,64925062108545024,3116402981210161152,
%U A009992 149587343098087735296,7180192468708211294208
%N A009992 Powers of 48.
%C A009992 If X_1, X_2, ..., X_n is a partition of the set {1,2,...,2*n} into blocks 
               of size 2 then, for n>=1, a(n) is equal to the number of functions 
               f : {1,2,..., 2*n}->{1,2,3,4,5,6,7} such that for fixed y_1,y_2,...,
               y_n in {1,2,3,4,5,6,7} we have f(X_i)<>{y_i}, (i=1,2,...,n). - Milan 
               R. Janjic (agnus(AT)blic.net), May 24 2007
%H A009992 T. D. Noe, <a href="b009992.txt">Table of n, a(n) for n=0..100</a>
%H A009992 Milan Janjic, <a href="http://www.pmfbl.org/janjic/">Enumerative Formulas 
               for Some Functions on Finite Sets</a>
%H A009992 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/
               RecursiveSequences.html">Recursive Sequences</a>
%F A009992 G.f.: 1/(1-48*x). [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 
               24 2008]
%Y A009992 Sequence in context: A156093 A063822 A158783 this_sequence A042105 A079240 
               A162700
%Y A009992 Adjacent sequences: A009989 A009990 A009991 this_sequence A009993 A009994 
               A009995
%K A009992 nonn
%O A009992 0,2
%A A009992 N. J. A. Sloane (njas(AT)research.att.com).

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