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Number of numbers k <= n such that at least one prime factor of n is not a prime factor of k.
6

%I #11 Apr 10 2018 21:45:58

%S 0,1,2,2,4,5,6,4,6,9,10,10,12,13,14,8,16,15,18,18,20,21,22,20,20,25,

%T 18,26,28,29,30,16,32,33,34,30,36,37,38,36,40,41,42,42,42,45,46,40,42,

%U 45,50,50,52,45,54,52,56,57,58,58,60,61,60,32,64,65,66,66,68,69,70,60

%N Number of numbers k <= n such that at least one prime factor of n is not a prime factor of k.

%H Robert Israel, <a href="/A010848/b010848.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = n-A003557(n). - _Vladeta Jovovic_, Sep 15 2006

%p f:= n -> n - n/convert(numtheory:-factorset(n),`*`):

%p map(f, [$1..100]); # _Robert Israel_, Apr 10 2018

%Y Cf. A008479, A010846, A010847.

%K nonn,easy

%O 1,3

%A _Olivier GĂ©rard_

%E Definition corrected by _Vladeta Jovovic_, Sep 15 2006