The geometric series is .

Find the common ratio.

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The common ratio is .

Find the sigma notation of the series.

The sigma notation of geometric series , where is upper bound.

Determine the upper bound by multiplying to the third term and so on.

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Since the geometric series has terms, the upper bound is .

The explicit formula for the sequence is .

Substitute and .

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Therefore, the sigma notation of the sequence is .

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