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%I #7 Apr 19 2022 22:45:20
%S 0,1,1,1,1,2,1,1,1,3,1,2,1,2,2,2,1,2,1,3,3,3,1,3,1,2,1,2,1,5,1,2,2,3,
%T 2,2,1,2,3,4,1,5,1,3,2,3,1,4,1,3,2,2,1,3,3,3,3,2,1,5,1,3,3,2,2,5,1,3,
%U 2,5,1,3,1,2,2,2,2,5,1,6,2,3,1,5,3,2,3,4,1,5,3,3,2,3,2,4,1,2,2,3,1,5,1,3,5
%N Number of divisors of n not in A353355.
%H Antti Karttunen, <a href="/A353381/b353381.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-A353380(d).
%F a(n) = A000005(n) - A353382(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 A332823(n) = { my(f = factor(n),u=(sum(k=1, #f~, f[k, 2]*2^primepi(f[k, 1]))/2)%3); if(2==u,-1,u); };
%o A353354(n) = sumdiv(n,d,A332823(d));
%o A353380(n) = (0==A353354(n));
%o A353381(n) = sumdiv(n,d,!A353380(d));
%Y Cf. A000005, A003961, A048675, A332823, A348717, A353352, A353354, A353355, A353380, A353382.
%K nonn
%O 1,6
%A _Antti Karttunen_, Apr 19 2022
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