Fibonacci sequence is defined by f(1)=1,f(2)=1 and f(m) =f(m-1)+f(m-2)
i.e. 1, 1, 2, 3, 5, 8, 13, ...
Prove that for all composite values of n>4, f(n) is composite.
(In reply to Fibs and primes
1. Since your Email address is hidden I use this channel
to convey some advice. Hope you don't mind.
2. Reasoning OK, but for the sake of claritu leave
paragraph 4. with a. and b. only , so that 4c will be par. 5.
3. Add paragraph 6., starting with : So we have proven ...etc
4. If you EDIT more than once , you may erase the previous remarks like "Edited..bla bla.." and leave only the last one.