find recursive for when n is positive

[ember niche]

I would like general steps on how to approach this type of problem

[drifting zephyr]

f(0) = 1
f(1) = f(1 - 1) - 1 = 0
f(2) = f(2 - 1) - 1 = -1
f(3) = f(3 - 1) - 1 = -2
...
from the pattern above we can conclude that
f(n) = -(n - 1)