f(n+1)=1,∀n∈{1,2,3} f(n+1) must be divisible by n ‌f(4)⇒−6,−3,0,3,6 ‌f(3)⇒−8,−6,−4,−2,0,2,4,6,8 ‌f(2)⇒−8,...............,8 ‌f(1)⇒−8,...............,8 ‌
f(4)
3
must be odd since f(3) should be even therefore 2 solution possible.