OFFSET
1,1
PROG
(PARI) u(n) = sumdiv(n, d, if(gcd(d, n/d)==1, d));
z(n) = sigma(n)-u(n);
for(n=1, 10^7, if(z(sigma(n))==2*n, print1(n, ", ")))
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Jason Earls, Aug 28 2001
STATUS
approved