Considering when you created your account, and the subject of your post, "troll" seemed like the most likely explanation. Sorry about that. (It's sort of a typical troll to make a technically incorrect statement and then watch people get all agitated as they correct you. In fact, it's one of my favorite trolls, right behind making a sarcastic statement which you know will be taken literally by half of the audience, a la "A Modest Proposal".)
Anyways, assuming that your comment was in earnest, the arrow is typically used for functions (or sequences). E.g.,
1/n -> 0 as n->infinity
You could write:
1/4 + 1/16 + ... + 1/4^n -> 1/3
But you would write
1/4 + 1/16 + ... = 1/3
You wouldn't write (or at least I've never seen it)
1/4 + 1/16 + ... -> 1/3
It's not really a mathematical issue, just a definitional one: the left hand side is considered a real number, not a sequence of real numbers (or function :N->R, or whatever).