Sum function of power series (∞Σn = 0) {((- 1) ^ n) * (x ^ 2n)} / N~

Sum function of power series (∞Σn = 0) {((- 1) ^ n) * (x ^ 2n)} / N~

E ^ (- x ^ 2) (minus sign outside x ^ 2)
You can look at the power series expansion of e ^ x, and then do variable substitution (because e ^ x is expanded on the whole real axis, so you don't have to worry about the convergence radius after variable substitution)