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Number of distinct digits needed to write in decimal representation all positive non-divisors of n that are less than n.
2

%I #5 Jan 06 2019 15:37:23

%S 0,0,1,1,3,2,5,4,6,6,10,6,10,9,9,9,10,9,10,9,10,10,10,10,10,10,10,10,

%T 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,

%U 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10

%N Number of distinct digits needed to write in decimal representation all positive non-divisors of n that are less than n.

%C a(n) = 10 for n > 20.

%e Set of non-divisors of n=12: {5,7,8,9,10,11}, therefore

%e a(12)=#{0,1,5,7,8,9}=6.

%t Table[Length[Union[Flatten[IntegerDigits/@Complement[Range[n],Divisors[ n]]]]],{n,80}] (* _Harvey P. Dale_, Jan 06 2019 *)

%Y Cf. A095048, A043537.

%K nonn,base

%O 1,5

%A _Reinhard Zumkeller_, May 28 2004