%N Smallest positive composite number, relatively prime to n, such that a(n)+n is also composite.
%C Does not include every composite number; in particular, 12 is not present. If a(n) = 12, gcd(n,12) = 1, but then one of n+4 and n+8 is divisible by 3.
%Y Equals A122985(n) - n. Cf. A096076.
%A _Franklin T. Adams-Watters_, Sep 22 2006