OFFSET
1,6
EXAMPLE
a(10) = 3: four, six and ten are semiprimes; nine is a semiprime relatively prime to ten.
PROG
(PARI) a(n) = sum(k=1, n, if (bigomega(k) == 2, gcd(k, n) != 1)); \\ Michel Marcus, Apr 15 2023
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Reikku Kulon, Sep 20 2008
STATUS
approved