DNA permutations and combinations

Can someone help me check if my work is correct?

Problem 1: Our genetic material, DNA, is formed from a 4 letter "alphabet" of bases: A, T, G, C (adenine, thymine, guanine, and cytosine). The order in which the letters are arranged is important, but because a molecule can move, there is no difference between a sequence and the same sequence reversed. For example, the sequence (A, A, T, A, G, A, T) is the same as the sequence (T, A, G, A, T, A, A). (In reality, DNA molecules have identifiable ends, but ignore that in this problem.)

How many distinct DNA sequences of 6 bases are there? (The answer to this particular question needs to be correct to one part in ten million.)

What I did was this: (4^6+4^6)/2 =4096

Is this correct? I don't get how "the answer to this particular question needs to be correct to one part in ten million" when my answer is only 4096

Any help would be greatly appreciated! Thank you!