sn=1+3/2^2+4/3^2+···+n/2^n-1+[n+1]/2^n

问题描述:

sn=1+3/2^2+4/3^2+···+n/2^n-1+[n+1]/2^n

Sn = 2/2 + 3/2^2 + 4/2^3 + …… + n/2^(n-1) + (n+1)/2^n(1/2)Sn = 2/2^2+ 3/2^3 + …… + n/2^n + (n+1)/2^(n+1)两式相减得(1/2)Sn= 1 + [ 1/2^2+ 1/2^3 +……+ 1/2^n ] - (n+1)/2^(n+1)= 1/2+ [ 1/2 + 1/2^2+ 1/...