YLL討論網

Let xyz≠0

and define f(n)=xⁿ+yⁿ+zⁿ  , 
g(n)=x^-n+y^-n+z^-n

If f(1)=1

   f(2)=2

   f(3)=3

then g(6) = ? f(18) = ?

(try to find the most convenient way to the question)