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I have a sequence {ai,1<= i <=k} where i know the sum of this sequence(say x).

I want to know the sum of another sequence {bi, 1<=i <=k}(at least a

*upper bound) where bi=ai*(1/2^i).*

**tight**Or in other words, if you know the sum of the

**ratio**sequence and sum of

**1 sequence**, how to find out the sum of the other sequence(can we)?

I tried using the convexity of 1/2^i, but couldn't get anything.

regards,

Bincy.