在数列{an}中,a1=1,a(n+1)=(1+1/n)an+（n+1/2^n）设bn=an/n,求bn的通项公式

1.a(n+1)=((n+1)/n)*an+(n+1)/2^n
a(n+1)/(n+1)=an/n+1/2^n
b(n+1)=bn+1/2^n
bn=b(n-1)+1/2^(n-1)
.
b2=b1+1/2^1
bn=b1+(1/2+1/2^2+...+1/2^(n-1))
bn=b1+1-1/2^(n-1)
bn=2-1/2^(n-1)
2.an=2n-n/2^(n-1)
sn=n(n+1)-(1+2/2+3/2^2+...+n/2^(n-1))
sn=n(n+1)-2*(1+2/2+3/2^2+...+n/2^(n-1)-1/2*(1+2/2+3/2^2+...+n/2^(n-1)))
sn=n(n+1)+2*(1+1/2+1/2^2+...+1/2^(n-1)-n/2^n)
sn=n(n+1)+2*(2-1/2^(n-1)-n/2^n)
sn=n(n+1)+4-(n+2)/2^(n-1)