Answer:
F(1) = 0
F(2) = -6 = 0 - 6 x 1 = F(1) - 6 x 1
F(3) = -12 = 0 - 6 x 2 = F(1) - 6 x 2
F(4) = -18 = 0 - 6 x 3 = F(1) - 6 x 3
...
F(n) = F(1) - 6 x (n - 1)
Hope this help!
:)
