>> PrimeQ[(1 + I)^4 - 1] >> True Franklin T. Adams-Watters: > Ah, but (1+i)^4 - 1 = -5, which is an *integer* prime, but *not* a > Gaussian prime. Oops... PrimeQ[(1 + I)^4 - 1, GaussianIntegers->True] False