cp's OEIS Frontend

A344774 Number of divisors d of n for which A049559(d) = A049559(n), where A049559(n) = gcd(n-1, phi(n)).

%I A344774 #8 Jun 30 2021 19:47:50
%S A344774 1,2,1,3,1,3,1,4,2,3,1,5,1,3,2,5,1,4,1,5,1,3,1,7,2,3,3,1,1,5,1,6,1,3,
%T A344774 1,7,1,3,2,7,1,5,1,5,2,3,1,9,2,4,2,1,1,5,1,6,1,3,1,9,1,3,3,7,1,1,1,5,
%U A344774 1,1,1,10,1,3,3,1,1,5,1,9,4,3,1,8,2,3,2,7,1,7,1,5,1,3,1,11,1,4,3,7,1,5,1,6,1
%N A344774 Number of divisors d of n for which A049559(d) = A049559(n), where A049559(n) = gcd(n-1, phi(n)).
%H A344774 Antti Karttunen, <a href="/A344774/b344774.txt">Table of n, a(n) for n = 1..65537</a>
%F A344774 a(n) = Sum_{d|n} [A049559(d) = A049559(n)], where [ ] is the Iverson bracket.
%F A344774 a(n) <= A330747(n).
%o A344774 (PARI)
%o A344774 A049559(n) = gcd(n-1, eulerphi(n));
%o A344774 A344774(n) = { my(x=A049559(n)); sumdiv(n,d,A049559(d)==x); };
%Y A344774 Cf. A000010, A049559, A330747.
%Y A344774 Cf. also A344773.
%K A344774 nonn
%O A344774 1,2
%A A344774 _Antti Karttunen_, May 31 2021