
Composite Fibonacci Terms
Problem
Let $F_n$ represents the $n^{th}$ term of the Fibonacci sequence: 1, 1, 2, 3, 5, 8, 13, ... .
Prove that for all composite values of $n \gt 4, F_n$ is composite.
Problem ID: 365 (03 Nov 2009) Difficulty: 4 Star

Let $F_n$ represents the $n^{th}$ term of the Fibonacci sequence: 1, 1, 2, 3, 5, 8, 13, ... .
Prove that for all composite values of $n \gt 4, F_n$ is composite.