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A163373
a(n) = phi(phi(sigma(n))).
1
1, 1, 1, 2, 1, 2, 2, 4, 4, 2, 2, 4, 2, 4, 4, 8, 2, 8, 4, 4, 8, 4, 4, 8, 8, 4, 8, 8, 4, 8, 8, 12, 8, 6, 8, 24, 6, 8, 8, 8, 4, 16, 8, 8, 8, 8, 8, 16, 12, 16, 8, 12, 6, 16, 8, 16, 16, 8, 8, 16, 8, 16, 16, 36, 8, 16, 16, 12, 16, 16, 8, 32, 12, 12, 16, 16, 16, 16, 16
OFFSET
1,4
COMMENTS
LINKS
FORMULA
MATHEMATICA
EulerPhi[EulerPhi[DivisorSigma[1, Range[100]]]] (* G. C. Greubel, Dec 20 2016 *)
PROG
(PARI) vector(100, n, eulerphi(eulerphi(sigma(n)))) \\ G. C. Greubel, Dec 20 2016
(Magma) [EulerPhi(EulerPhi(SumOfDivisors(n))): n in [1..80]]; // Vincenzo Librandi, Dec 20 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Jul 25 2009
STATUS
approved