(1)bn-b(n-1)=(an+3)/2^n-(a(n-1)+3)/2^(n-1)=1,所以bn是以b1=0,公差为1的等差数列;
(2)bn的通项公式为:bn=n-1,又bn=(an+3)/2^n,所以(an+3)/2^n=n-1,求得
an=(n-1)2^n-3
(1)bn-b(n-1)=(an+3)/2^n-(a(n-1)+3)/2^(n-1)=1,所以bn是以b1=0,公差为1的等差数列;
(2)bn的通项公式为:bn=n-1,又bn=(an+3)/2^n,所以(an+3)/2^n=n-1,求得
an=(n-1)2^n-3