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A163375
a(n) = sigma(tau(phi(n))).
2
1, 1, 3, 3, 4, 3, 7, 4, 7, 4, 7, 4, 12, 7, 7, 7, 6, 7, 12, 7, 12, 7, 7, 7, 12, 12, 12, 12, 12, 7, 15, 6, 12, 6, 15, 12, 13, 12, 15, 6, 15, 12, 15, 12, 15, 7, 7, 6, 15, 12, 12, 15, 12, 12, 15, 15, 13, 12, 7, 6, 28, 15, 13, 12, 18, 12, 15, 12, 12, 15, 15, 15
OFFSET
1,3
LINKS
FORMULA
MATHEMATICA
DivisorSigma[1, DivisorSigma[0, EulerPhi[Range[100]]]] (* G. C. Greubel, Dec 20 2016 *)
PROG
(PARI) vector(100, n, sigma(numdiv(eulerphi(n)))) \\ G. C. Greubel, Dec 20 2016
(Magma) [SumOfDivisors(NumberOfDivisors(EulerPhi(n))): n in [1..80]]; // Vincenzo Librandi, Dec 20 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Jul 25 2009
STATUS
approved