Find a formula for the nth partial sum of the series and use it to find the series' sum if the series converges 6 6 6 6 6+ 7 49 343 70 -1 The formula for the nth partial sum, Sn. of the series is If the series converges, what is the series' sum? Select the correct choice below and, if necessary, fill in the answer box to complete your choice. O A. The series converges. The series' sum is (Type an integer or a simplified fraction.) O B. The series diverges. rce urces ns