[codewars]5.Series: 1 + 14 + 17 + 110 + 113 + 116 +...

SeriesSum(1) => 1 = “1” SeriesSum(2) => 1 + 1/4 = “1.25” SeriesSum(5) => 1 + 1/4 + 1/7 + 1/10 + 1/13 = “1.57”

# my_version 这里写代码片（unfinished） # best_solution def series_sum(n): return '{:.2f}'.format(sum(1.0/(3 * i + 1) for i in range(n)))