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%I #8 Apr 23 2023 22:45:37
%S 1,2,1,3,1,4,1,4,1,2,1,6,1,2,1,5,1,6,1,5,1,2,1,8,1,2,1,3,1,4,1,6,1,2,
%T 1,9,1,2,1,7,1,6,1,3,1,2,1,10,1,2,1,3,1,8,1,4,1,2,1,8,1,2,1,7,1,4,1,3,
%U 1,2,1,12,1,2,1,3,1,4,1,9,1,2,1,11,1,2,1,4,1,6,1,3,1,2
%N Number of divisors d of n such that phi(d) | n.
%F a(n) = Sum_{d|n, phi(d)|n} 1.
%t a[n_] := DivisorSum[n, 1 &, Divisible[n, EulerPhi[#]] &]; Array[a, 100] (* _Amiram Eldar_, Apr 22 2023 *)
%o (PARI) a(n) = sumdiv(n, d, !(n % eulerphi(d))); \\ _Michel Marcus_, Apr 22 2023
%Y Cf. A000010, A069932.
%K nonn,easy
%O 1,2
%A _Wesley Ivan Hurt_, Apr 21 2023