<image>Define an operation "F" for a positive integer $$n$$:
$$①$$ When $$n$$ is odd, the result is $$3n+5$$; 
$$②$$ When $$n$$ is even, the result is $$\dfrac{n}{2^{k}}$$ (where $$k$$ is the positive integer such that $$\dfrac{n}{2^{k}}$$ is odd), and the operation is repeated.
For example, if $$n=26$$, then: if $$n=449$$, the result of the 449th "F" operation is ______.
