OFFSET
1,3
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
FORMULA
EXAMPLE
a(4) = 0 because 4 is not squarefree and phi(4) - A073311(4) = 2 - 2 = 0.
PROG
(PARI) a(n)=my(s=sum(i=1, n, gcd(n, i)==1&&issquarefree(i))); if(issquarefree(n), s, eulerphi(n)-s) \\ Charles R Greathouse IV, Nov 05 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Irina Gerasimova, Nov 03 2013
EXTENSIONS
a(4) corrected and a(54) inserted by Charles R Greathouse IV, Nov 05 2013
STATUS
approved