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Number of divisors of n that are not in A325698.
3

%I #7 Apr 20 2022 09:58:21

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

%T 2,6,1,2,3,7,1,5,1,5,4,3,1,8,2,5,2,4,1,6,3,6,3,2,1,9,1,3,5,6,2,5,1,5,

%U 2,5,1,9,1,2,4,4,2,5,1,9,4,3,1,8,3,2,3,7,1,8,3,5,2,3,2,10,1,4,4,8,1,5,1,6,5

%N Number of divisors of n that are not in A325698.

%H Antti Karttunen, <a href="/A353371/b353371.txt">Table of n, a(n) for n = 1..65537</a>

%H <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>

%F a(n) = Sum_{d|n} 1-A353370(d).

%F a(n) = A000005(n) - A353372(n).

%F a(p) = 1 for all primes p.

%F a(n) = a(A003961(n)) = a(A348717(n)), for all n >= 1.

%o (PARI)

%o A353370(n) = { my(f = factor(n)); (0==sum(i=1, #f~, f[i,2]*((-1)^(primepi(f[i, 1])%2)))); };

%o A353371(n) = sumdiv(n,d,!A353370(d));

%Y Cf. A000005, A003961, A325698, A348717, A353370, A353372.

%K nonn

%O 1,4

%A _Antti Karttunen_, Apr 16 2022