OFFSET
1,2
COMMENTS
Powers of primes (A000961) are in this sequence.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
PROG
(PARI) a071324(n) = my(d=Vecrev(divisors(n))); sum(k=1, #d, (-1)^(k+1)*d[k]);
a206369(n) = a(n) = sumdiv(n, d, eulerphi(n/d) * issquare(d));
isok(n) = a071324(n) == a206369(n);
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Marcus, Aug 11 2018
STATUS
approved