first n should be divisible by 3 and 5 since phi(n) is the number of the positive integers relatively prime with n
so phi(n) is integer for all n.
suppose n is divisible by another prime p, say
[tex] n = 3^r 5^s p^t...(1) [/tex]
g is multiplicative
[tex]g(n) = g(3^r)\cdot g(5^s)\cdot g(p^t) [/tex]