The sequence ana_nan is defined by an=5⋅(13)n−1a_n = 5 \cdot (\frac{1}{3})^{n-1}an=5⋅(31)n−1. What is the value of the infinite sum ∑n=1∞an\sum_{n=1}^{\infty} a_n∑n=1∞an?
7.57.57.5
2.52.52.5
555
151515