Prove that If $f_n$ where $n>3$ is prime, then $n$ is prime for a Fibonacci series where $f_1$=$f_2$=1

Question

This problem came up in my conversation with a friend—not sure how basic it is, but it seems quite interesting:

Prove that if $f_n$ where $n>3$ is prime, then $n$ is prime for a Fibonacci sequence where $f_1=f_2=1.$

How can this be tackled? Thanks a bunch for any ideas.

Basically it suffices to show, that $f_n$ is a divisibility sequence - it is shown in the link posted in the answer and also here: http://math.stackexchange.com/questions/60340/fibonacci-modular-results/60353#60353 — Martin Sleziak, Oct 08 '11 at 15:31

score 2 · Accepted Answer · answered Feb 20 '11 at 08:02

2

The answer may be found at this link:

answered Feb 20 '11 at 08:02

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