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A065864 Remainder when n is divided by the number of nonprimes not exceeding n. 7

%I

%S 0,0,0,0,1,0,1,0,4,4,5,5,6,6,6,6,7,7,8,8,8,8,9,9,9,9,9,9,10,10,11,11,

%T 11,11,11,11,12,12,12,12,13,13,14,14,14,14,15,15,15,15,15,15,16,16,16,

%U 16,16,16,17,17,18,18,18,18,18,18,19,19,19,19,20,20,21,21,21,21,21,21

%N Remainder when n is divided by the number of nonprimes not exceeding n.

%H Harry J. Smith, <a href="/A065864/b065864.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = n mod (n-pi(n)) = n mod (n-A000720(n)) = n mod A062298(n).

%e For n=100, pi(100)=25, so a(100) = 100 mod (100-25) = 25.

%t Table[Mod[n, n - PrimePi@ n], {n, 78}] (* or *)

%t Table[Mod[n, Count[Range@ n, k_ /; ! PrimeQ@ k]], {n, 78}] (* _Michael De Vlieger_, Jan 01 2017 *)

%o (PARI) { for (n = 1, 1000, a=n%(n - primepi(n)); write("b065864.txt", n, " ", a) ) } \\ _Harry J. Smith_, Nov 02 2009

%Y Cf. A000040, A004648, A062298, A065133, A065134, A065858-A065864.

%K nonn

%O 1,9

%A _Labos Elemer_, Nov 26 2001

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Last modified April 20 09:59 EDT 2019. Contains 322309 sequences. (Running on oeis4.)