数列3/2,9/4,25/8,65/16…前n项的和为?

数列3/2,9/4,25/8,65/16…前n项的和为?
数列3/2,9/4,25/8,65/16…前n项的和为?

数列3/2,9/4,25/8,65/16…前n项的和为?
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