OFFSET
1,2
COMMENTS
a(2n)>a(2n+1) for n>=5.
If n is prime, a(n) = A002088(n)+1. - Robert Israel, Aug 10 2020
LINKS
Robert Israel, Table of n, a(n) for n = 1..2000
MAPLE
f:= n -> add(numtheory:-phi(n*k), k=1..n)/numtheory:-phi(n);
map(f, [$1..100]); # Robert Israel, Aug 10 2020
MATHEMATICA
Table[1/EulerPhi[n]*Sum[EulerPhi[n*k], {k, n}], {n, 60}] (* Harvey P. Dale, Dec 21 2015 *)
PROG
(PARI) for(n=1, 100, print1(sum(i=1, n, eulerphi(n*i))/eulerphi(n), ", "))
CROSSREFS
KEYWORD
AUTHOR
Benoit Cloitre, May 13 2002
STATUS
approved