What is the sum of the first 18 terms of the series 2, 8, 32...

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The given series consisting of 2, 8, 32... is a geometric progression with common ratio 8/2 = 32/8 = 4 and the first term is 2.

For a geometric progression the sum of the first n terms is `a*(r^n - 1)/(r - 1)` . Substituting the given values:

`S_18 = 2*(4^18 - 1)/(4 - 1)`

= `2*(4^18 -1)/3`

The required sum is `2*(4^18 -1)/3`

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