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%I #15 Jun 17 2018 02:00:03
%S 0,1,2,2,4,7,6,4,6,13,10,14,12,19,22,8,16,21,18,26,32,31,22,28,20,37,
%T 18,38,28,59,30,16,52,49,58,42,36,55,62,52,40,85,42,62,66,67,46,56,42,
%U 65,82,74,52,63,94,76,92,85,58,118,60,91,96,32,112
%N a(n) = n * Sum_{primes p dividing n} (1 - 1/p).
%C For a prime p, a(p) = phi(p), where phi is Euler's totient function. - _Alonso del Arte_, Jun 16 2012
%H Harry J. Smith, <a href="/A065968/b065968.txt">Table of n, a(n) for n = 1..1000</a>
%e a(10) = 13 because 10 is divisible by the primes 2 and 5, and 10*(1/2 + 4/5) = 13.
%o (PARI) { for (n=1, 1000, s=0; p=2; while (p<=n, if(n%p == 0, s+=1 - 1/p); p=nextprime(p + 1)); write("b065968.txt", n, " ", n*s) ) } \\ _Harry J. Smith_, Nov 05 2009
%Y Cf. A000010 (same definition except for the crucial difference of product instead of sum for the 1 - 1/p).
%K nonn
%O 1,3
%A _N. J. A. Sloane_, Dec 09 2001
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