Determine the number of functions f from the integers to \{1,2, \cdots, 15\} which satisfy
f(x)=f(x+15)
and
f(x+f(y))=f(x-f(y))
for all x, y.
Determine the number of functions f from the integers to \{1,2, \cdots, 15\} which satisfy
and
for all x, y.