A geometric sequence is defined recursively by an = 4an–1. The 1st term of the sequence is 0.5. Which of the following is the explicit formula for the nth term of the sequence?
1) an = 4 ⋅ 0.5(n – 1)
2) an = 0.5 ⋅ 4(n + 1)
3) an = 0.5 ⋅ 4n
4) an = 0.5 ⋅ 4(n – 1)
5) an = 4 ⋅ 0.5n