OFFSET
1,4
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
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