Let $R(n)$ be the repetition of $n$, e.g. $R(1)=11$, $R(120)=120120$ etc.
$R(5)=55$ is a Fibonacci number, the only one I found.
Is $55$ really the only repetition in Fibonacci sequence?
If not, is the set of all $n$ such that $R(n)$ is a Fibonacci number, finite or not?
// own question, I don't know neither the solution not the answer...