OFFSET
1,1
EXAMPLE
5 is in the sequence since sopf(5) - pi(5) = 5 - 3 = 2 = tau(5).
PROG
(PARI) sopf(n, fac) = fac=factor(n); sum(i=1, matsize(fac)[1], fac[i, 1]); pi(x, c) = forprime(p=2, x, c++); c for(n=1, 10^6, if(sopf(n)-pi(n)==numdiv(n), print(n)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Jason Earls, Oct 02 2001
EXTENSIONS
More terms from Klaus Brockhaus, Oct 05 2001. No further term < 800000.
Corrected offset and a(15)-a(27) from Donovan Johnson, Mar 10 2010
STATUS
approved