A362470 Number of divisors d of n such that phi(d) | n.
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, 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, 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
Offset: 1
Programs
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Mathematica
a[n_] := DivisorSum[n, 1 &, Divisible[n, EulerPhi[#]] &]; Array[a, 100] (* Amiram Eldar, Apr 22 2023 *)
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PARI
a(n) = sumdiv(n, d, !(n % eulerphi(d))); \\ Michel Marcus, Apr 22 2023
Formula
a(n) = Sum_{d|n, phi(d)|n} 1.