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A322019 a(n) = A000005(n) - A014197(n), where A000005(n) gives the number of divisors of n, and A014197(n) gives the number of integers m with phi(m) = n.

%I A322019 #10 Dec 03 2018 18:29:21
%S A322019 -1,-1,2,-1,2,0,2,-1,3,2,2,0,2,4,4,-1,2,2,2,1,4,2,2,-2,3,4,4,4,2,6,2,
%T A322019 -1,4,4,4,1,2,4,4,-1,2,4,2,3,6,2,2,-1,3,6,4,4,2,6,4,5,4,2,2,3,2,4,6,
%U A322019 -1,4,6,2,6,4,6,2,-5,2,4,6,6,4,6,2,0,5,2,2,6,4,4,4,2,2,12,4,3,4,4,4,-5,2,6,6,5,2,6,2,5,8
%N A322019 a(n) = A000005(n) - A014197(n), where A000005(n) gives the number of divisors of n, and A014197(n) gives the number of integers m with phi(m) = n.
%H A322019 Antti Karttunen, <a href="/A322019/b322019.txt">Table of n, a(n) for n = 1..20790</a>
%H A322019 Antti Karttunen, <a href="/A322019/a322019.txt">Data supplement: n, a(n) computed for n = 1..100000</a>
%F A322019 a(n) = A000005(n) - A014197(n).
%o A322019 (PARI)
%o A322019 A014197(n, m=1) = { n==1 && return(1+(m<2)); my(p, q); sumdiv(n, d, if( d>=m && isprime(d+1), sum( i=0, valuation(q=n\d, p=d+1), A014197(q\p^i, p))))}; \\ From A014197
%o A322019 A322019(n) = (numdiv(n)-A014197(n));
%Y A322019 Cf. A000005, A014197, A305058 (positions of zeros).
%Y A322019 Cf. also A305896.
%K A322019 sign
%O A322019 1,3
%A A322019 _Antti Karttunen_, Dec 03 2018