Search: id:A055846
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%I A055846
%S A055846 1,4,25,150,900,5400,32400,194400,1166400,6998400,41990400,251942400,
%T A055846 1511654400,9069926400,54419558400,326517350400,1959104102400,
%U A055846 11754624614400,70527747686400,423166486118400,2538998916710400
%N A055846 A second order recursive sequence.
%C A055846 For n>=2, a(n) is equal to the number of functions f:{1,2,...,n}->{1,
               2,3,4,5,6} such that for fixed, different x_1, x_2 in {1,2,...,n} 
               and fixed y_1, y_2 in {1,2,3,4,5,6} we have f(x_1)<>y_1 and f(x_2)<> 
               y_2. - Milan R. Janjic (agnus(AT)blic.net), Apr 19 2007
%D A055846 A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, 
               pps. 194-196.
%H A055846 Milan Janjic, <a href="http://www.pmfbl.org/janjic/">Enumerative Formulas 
               for Some Functions on Finite Sets</a>
%F A055846 a(n)=25*6^(n-2), a(0)=1, a(1)=4. a(n)=6a(n-1)+[(-1)^n]*binomial(2, 2-n); 
               G.f.(x)=(1-x)^2/(1-6x).
%Y A055846 First differences of A052934. Cf. A000400.
%Y A055846 Sequence in context: A015533 A079291 A072221 this_sequence A091634 A010909 
               A079750
%Y A055846 Adjacent sequences: A055843 A055844 A055845 this_sequence A055847 A055848 
               A055849
%K A055846 easy,nonn
%O A055846 0,2
%A A055846 Barry E. Williams, Jun 03 2000
%E A055846 More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jun 05 2000

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