For 2, show each of the following: a) n 2-satisfies the equation sigma (n)=2n - 1. ub) if 2 1 is prime, then n 2-1(2-1 ) satisfies the equation o (n) = 2n. if 2-3 is prime, then n 2-1(2-3) satisfies o (n) = 2n +2. it is not known if there are any positive integers n for which a (n) 2n + 1.