A353636 Difference between phi(sigma(n)) and phi(n).
0, 1, 0, 4, -2, 2, -2, 4, 6, 2, -6, 8, -6, 2, 0, 22, -10, 18, -10, 4, 4, 2, -14, 8, 10, 0, -2, 12, -20, 16, -14, 20, -4, 2, -8, 60, -18, -2, 0, 8, -28, 20, -22, 4, 0, 2, -30, 44, -6, 40, -8, 18, -34, 14, -16, 8, -4, -4, -42, 32, -30, 2, 12, 94, -24, 28, -34, 4, -12, 24, -46, 72, -36, 0, 20, 12, -28, 24, -46, 28, 56
Offset: 1
Links
- Antti Karttunen, Table of n, a(n) for n = 1..10000
- Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65537
- Index entries for sequences related to sigma(n)
Crossrefs
Programs
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Mathematica
a[n_] := EulerPhi[DivisorSigma[1, n]] - EulerPhi[n]; Array[a, 100] (* Amiram Eldar, May 06 2022 *)
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PARI
A353636(n) = (eulerphi(sigma(n))-eulerphi(n));