Sequence 3 / 2, 9 / 4, 25 / 8, 65 / 16 The sum of the first n items is?

3/2,9/4,25/8,65/16,…
=1+1/2+2+1/4+3+1/8+.+n+1/2^n
=(1+2+3+...+n)+[1/2+1/4+...+1/2^n]
=n(n+1)/2+1-1/2^n

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