Either this question is the easiest one on StackExchange or I just don't get it. The question is :
"Let F(n) be the number of strings of length n over an alphabet of size k. Derive a recurrence relation for F(n)."
Clearly, $ F(n)=k^n $ since for every 'letter' we have k choices and there are n letters. And also F(0) = 1 and F(1) = k. How to derive a recurrence relation for this? Thank you in advance and be safe.