If the coefficients of the first three terms in the expansion of (x ^ 1 / 2 + 1 / (2 ^ 4 * x ^ - 1 / 2)) ^ n form an arithmetic sequence, (1) Find n How to do it? When answering, please use words directly. For example, the 5th power of 3 Or I'll look dizzy

If the coefficients of the first three terms in the expansion of (x ^ 1 / 2 + 1 / (2 ^ 4 * x ^ - 1 / 2)) ^ n form an arithmetic sequence, (1) Find n How to do it? When answering, please use words directly. For example, the 5th power of 3 Or I'll look dizzy

n>=2
Then s (n-1) is meaningful
an=Sn-S(n-1)=(2^n+3)-[2^(n-1)-3]=2^n-2^(n-1)
=2×2^(n-1)-2^(n-1)
=2^(n-1)
So n > = 2, an = 2 ^ (n-1)