OFFSET
1,6
COMMENTS
a(n) > 1 if and only if the prime factorization of n contains at least two distinct primes, p and q, such that q = prime(p).
LINKS
FORMULA
a(n) = gcd(n, A064988(n)).
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Sep 11 2018
STATUS
approved