OFFSET
1,2
COMMENTS
See A370689 for details.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Jean-Marie De Koninck and Florian Luca, On the composition of the Euler function and the sum of divisors function, Colloquium Mathematicum, Vol. 108, No. 1 (2007), pp. 31-51.
MATHEMATICA
Table[DivisorSigma[1, EulerPhi[n]]/EulerPhi[DivisorSigma[1, n]], {n, 1, 100}] // Denominator
PROG
(PARI) a(n) = {my(f = factor(n)); denominator(sigma(eulerphi(f)) / eulerphi(sigma(f))); }
CROSSREFS
KEYWORD
nonn,easy,frac
AUTHOR
Amiram Eldar, Feb 27 2024
STATUS
approved