Given the sequence an = 1 / (3 ^ (n-1)), the sum of the first n terms is SN. It is proved that for all n ∈ n *, Sn

N is any element in the positive integer set. From an = 1 / (3 ^ (n-1)) = (1 / 3) ^ (n-1), we can see that the first term is when n = 1, A1 = 1, and the common ratio is q = 1 / 3. It is an infinitely decreasing equal ratio sequence, so Sn has a range, and the minimum is 1

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