OFFSET
1,3
COMMENTS
To every fraction taken by the arithmetical function m -> phi(m)/m there is exactly one n such that a(n)/A225680(n) is equal to it.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
EXAMPLE
A005117(5) = 6, phi(6)/6 = 2/6 = 1/3, so a(5) = 1.
MATHEMATICA
s = Select[Range[200], SquareFreeQ]; Numerator[EulerPhi[s]/s] (* T. D. Noe, May 13 2013 *)
PROG
(PARI) lista(nn) = apply(x->(numerator(eulerphi(x)/x)), Vec(select(issquarefree, [1..nn], 1))); \\ Michel Marcus, Feb 22 2021
CROSSREFS
KEYWORD
nonn,frac,easy
AUTHOR
Franz Vrabec, May 12 2013
STATUS
approved