Oops, typo. You're right. You could also write "e^tau*i = 1 + 0" to relate the "5 most important numbers in math" but that form always seemed a bit forced to me.

If you write "-1 * e^(tau * i) + 1 = 0" you can reasonably claim to relate six important numbers: -1, e, tau, i, 1, and 0. IMHO that looks a bit less forced than the version with "1 + 0", though of course it's not the simplest form. (I mean, that "+ 0" could have been inserted almost anywhere...)