Solution: b (n+1) = 2bn+2 ∴ b (n+1)+2 = 2bn+4 = 2 (bn+2) b1= a2-a1= 4-. =1) ∴ bn = 2 (n+1)-2: bn = a (n+1)-an ∴ b (n-1) = an-a (n- B 1=a2-a 1 Add the above formulas to get BN+B (n-1)+...+B1= A (n+1)-A1∵ -2+...+2 2-2+2 1 = 2( 1-2n)/( 1-2)-2(n- 1)= 2(n+65438+。 = 1) a 1+a2+...+an=2^2-2+2^3-4+...+2^(n+ 1)-2n =2^2+2^3+...+2^(n+ 1)-