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 A065970 a(n) = n^2 * Sum_{primes p dividing n} (1 - 1/p^2). 1

%I #9 Jun 17 2018 02:00:10

%S 0,3,8,12,24,59,48,48,72,171,120,236,168,339,416,192,288,531,360,684,

%T 824,843,528,944,600,1179,648,1356,840,2339,960,768,2048,2019,2376,

%U 2124,1368,2523,2864,2736,1680,4619,1848,3372,3744,3699,2208

%N a(n) = n^2 * Sum_{primes p dividing n} (1 - 1/p^2).

%H Harry J. Smith, <a href="/A065970/b065970.txt">Table of n, a(n) for n = 1..1000</a>

%o (PARI) { for (n=1, 1000, s=0; p=2; while (p<=n, if(n%p == 0, s+=1 - 1/p^2); p=nextprime(p + 1)); write("b065970.txt", n, " ", n^2*s) ) } \\ _Harry J. Smith_, Nov 05 2009

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Dec 09 2001

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Last modified September 25 02:38 EDT 2023. Contains 365582 sequences. (Running on oeis4.)