Question

数列an满足a1=2 an+1=2^(n+1)an/【(n+1/2)an+1+2^n】{两个an+1的（n+1）是下标}

Answer 1

(1).bn=1/2*(n^2+1)

(2).cn=1/[n*(n+1)]*[2^(-n-1)]*(n+1/2+bn)=1/2^(n+2)+1/2^(n+2)*[1/n+1/n*(n+1)]

=1/2^(n+2)+[1/2^(n+1)*1/n-1/2^(n+2)*1/(n+1)]=dn+cn

Sdn是等比数列好算

把cn的前n项相加可减到很多项,剩余1/2^(n+2)*1/(n+1),1/4这两项

你再算一遍吧