The {an} is an equal ratio sequence, the sum of the first n terms is Sn, and Sn = 2 to the nth power + a (n ∈ n} to find the value of a and the common term of {α n} The {an} is an equal ratio sequence, the sum of the first n terms is Sn, and Sn = the nth power of 2 + a (n ∈ n ＊) The general formula of a value and {α n} If BN = (2n-1) an, find the first n terms and TN of the sequence {BN} Urgent,

The {an} is an equal ratio sequence, the sum of the first n terms is Sn, and Sn = 2 to the nth power + a (n ∈ n} to find the value of a and the common term of {α n} The {an} is an equal ratio sequence, the sum of the first n terms is Sn, and Sn = the nth power of 2 + a (n ∈ n ＊) The general formula of a value and {α n} If BN = (2n-1) an, find the first n terms and TN of the sequence {BN} Urgent,

Because Sn = 2 ^ n + a when n ≥ 2, an = SN-S (n-1) = 2 ^ n + A-2 ^ (n-1) - a = 2 ^ (n-1) when n = 1, A1 = S1 = 2 + A, A1 = 2 ^ 0 = 1 from an = 2 ^ (n-1), so 2 + a = 1, that is, a = - 1, so the general terms of {an} are an = 2 ^ (n-1) 2, BN = (2n-1) * 2 ^ (n-1) = n * 2 ^ n-2 ^ (n-1) and the sum of the first n terms of {n * 2 ^ n} is kn