OPEN
Let $f(1)=f(2)=1$ and for $n>2$
\[f(n) = f(n-f(n-1))+f(n-f(n-2)).\]
Does $f(n)$ miss infinitely many integers? What is its behaviour?
Asked by Hofstadter. The sequence begins $1,1,2,3,3,4,\ldots$ and is
A005185 in the OEIS. It is not even known whether $f(n)$ is well-defined for all $n$.
