!!!!!!!! 50 POINTS !!!!!!!!What are the explicit equation and domain for a geometric sequence with a first term of 2 and a second term of −8?

an = 2(−8)^(n − 1); all integers where n ≥ 1
an = 2(−8)^(n − 1); all integers where n ≥ 0
an = 2(−4)^(n − 1); all integers where n ≥ 0
an = 2(−4)^(n − 1); all integers where n ≥ 1