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A125945 a(n) is the number of nonnegative integers k less than 10^n such that the decimal representation of k lacks at least one of digits 1,2, at least one of digits 3,4 and at least one of digits 5,6,7,8,9.

%I A125945 #13 Sep 24 2015 11:41:23
%S A125945 10,96,892,8076,71500,619236,5241652,43355436,350740540,2780210676,
%T A125945 21641505412,165814383996,1253254845580,9362782430916,69259450905172,
%U A125945 508062802935756,3700662365318620,26794126632247956,193018363703408932,1384505203965202716
%N A125945 a(n) is the number of nonnegative integers k less than 10^n such that the decimal representation of k lacks at least one of digits 1,2, at least one of digits 3,4 and at least one of digits 5,6,7,8,9.
%H A125945 Colin Barker, <a href="/A125945/b125945.txt">Table of n, a(n) for n = 1..1000</a>
%H A125945 Milan Janjic, <a href="http://www.pmfbl.org/janjic/">Enumerative Formulas for Some Functions on Finite Sets</a>
%H A125945 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (28,-322,1960,-6769,13132,-13068,5040).
%F A125945 a(n) = 20*7^n-60*6^n+85*5^n-70*4^n+34*3^n-9*2^n+1.
%F A125945 G.f.: -2*x*(2520*x^6 -6054*x^5 +6063*x^4 -2794*x^3 +712*x^2 -92*x +5) / ((x -1)*(2*x -1)*(3*x -1)*(4*x -1)*(5*x -1)*(6*x -1)*(7*x -1)). - _Colin Barker_, Feb 23 2015
%p A125945 f:=n->20*7^n-60*6^n+85*5^n-70*4^n+34*3^n-9*2^n+1;
%o A125945 (PARI) a(n)=20*7^n-60*6^n+85*5^n-70*4^n+34*3^n-9*2^n+1 \\ _Charles R Greathouse IV_, Sep 24 2015
%Y A125945 Cf. A125630.
%K A125945 nonn,base,easy
%O A125945 1,1
%A A125945 Aleksandar M. Janjic and _Milan Janjic_, Feb 04 2007