Search: id:A055275
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%I A055275
%S A055275 1,8,72,648,5832,52488,472392,4251528,38263752,344373768,3099363912,
%T A055275 27894275208,251048476872,2259436291848,20334926626632,183014339639688,
%U A055275 1647129056757192,14824161510814728,133417453597332552
%N A055275 First differences of 9^n (A001019).
%C A055275 For n>=1, a(n) is equal to the number of functions f:{1,2...,n}->{1,2,
               3,4,5,6,7,8,9} such that for a fixed x in {1,2,...,n} and a fixed 
               y in {1,2,3,4,5,6,7,8,9} we have f(x)<>y. - Aleksandar M. Janjic 
               and Milan R. Janjic (agnus(AT)blic.net), Mar 27 2007
%D A055275 A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, 
               pps. 194-196.
%H A055275 Milan Janjic, <a href="http://www.pmfbl.org/janjic/">Enumerative Formulas 
               for Some Functions on Finite Sets</a>
%e A055275 G.f.: (1-x)/(1-9x). a(n)=8*9^(n-1); a(0)=1. a(n)=9a(n-1)+[(-1)^n]*C(1,
               1-n).
%Y A055275 Cf. A001019.
%Y A055275 Sequence in context: A062541 A057091 A156566 this_sequence A155198 A147840 
               A115970
%Y A055275 Adjacent sequences: A055272 A055273 A055274 this_sequence A055276 A055277 
               A055278
%K A055275 easy,nonn
%O A055275 0,2
%A A055275 Barry E. Williams, May 28 2000
%E A055275 More terms from James A. Sellers (sellersj(AT)math.psu.edu), May 29 2000

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