Email the mods to have the title edited, [email protected]; it’s a worthwhile change here.
“in 2^[0.6039n+o(n)] time” could be a better edit than the paper’s provided title, though I selected [] rather than {} for human use. I defer to experts in the field on whether it matters to declare O(n) or not.
You'll want small o, not big O. Otherwise there's no point in mentioning the constant factor 0.6039.
And yes the o(n) is relevant. Though I guess implied to some extent.
Changing {} to [] seems like a very strange suggestion to me. {} is used here because it's the way you group things in LaTeX. If you were going to change it for human use, why not just use parenthesis? What's wrong with {} in the first place?